A fuzzy data meta training system for ranking hub container terminals

The potential and critical aspects of any transport service can be highlighted through the estimation of appropriate performance indicators of the examined system. Commonly, container terminal analysis is based first on the evaluation and comparison of quantitative parameters that describe the level of service of the terminal and, on the other side by means of performance indicators related to terminal productivity. In this paper a Fuzzy Inference System for evaluation of a synthetic performance indicator is proposed. This tool could help planners and managers in terminals performances analysis and ranking as well as in assessing the effects of possible intervention on the systems. The proposed approach is suitable in the case of hub container ports. In fact this system is characterised by significant uncertainties and it is not always governed by certain rules, rational behaviour, so that it cannot be easily represented by traditional mathematical techniques and models. In our opinion, could be convenient to define the values of the considered parameters by explicitly define them in an approximate way, that is to say by fuzzy sets

Full Scale Validation Of A High Pressure Ratio Centrifugal Compressor

LectureThe present paper describes the test activities which have validated a new compressor architecture, developed by the OEM, which is able to deliver a higher pressure ratio in a single casing with respect to traditional configurations. The major differences with respect to the typical technologies used for high pressure machines are in the rotor design: Rotor stacked configuration with impellers connected through high precision toothed joint and a pre-stretched tie-rod; Shrouded and unshrouded impellers on a multistage between-bearings compressor; High peripheral speed journal and thrust bearings. The combination of unshrouded and shrouded impellers allows achieving same pressure ratio in a shorter bearing span, giving the possibility to increase the number of sections for each unit, making possible to reduce the number of casings. A full scale prototype has been built and tested to validate the new machine architecture. The prototype has been designed to fulfill a compression service made of three compression sections with a single unit; the same service could only be performed with at least two units if a standard compressor design was applied. The service requires serial compression of natural gas, characterized as follows: Design inlet volumetric flow close to10800m3/h; Design pressure ratio close to 30; Absorbed power~14MW; Design speed of 17619 RPM (MCS = 18500RPM, mos = 14095 RPM); First section comprises 2 open impellers; second section comprises 3 closed impellers and third section has 2 closed impellers. Impellers for first and second sections are in stacked configuration; third section’s impellers are mounted through shrink fitting. Considering the increased speed requirement, the prototype has been tested in conjunction with an epicyclic gear, which allows for improved efficiency for high gear ratio (12.34 in this case) with respect to standard parallel axes gears

A Numerical Study of Bubbles Captured by a Gaussian Vortex

The capture mechanics of cavitation nuclei by a Gaussian Vortex is explored. The capture process is examined by both Direct Numerical Simulation of the Navier Stokes equations and a Particle Tracking model. We also investigate the parameters that effect the capture and bubble growth process, and finally we compare the results of the two approaches. The DNS results show that the shape of the bubbles can be significantly distorted as they are captured by a vortex. This distortion can lead to the creation of lift forces that shorten the capture time of the bubbles. The capture times computed with the two methods varied over less than an order of magnitude for most cases, and this suggests that one might derive and average capture time. The exact results of the particle tracking models can vary widely depending on the selected values of the lift and drag coefficients and nominal Weber number of the captured nucleus. For model scale flows, the Weber number may vary from 1 to 100. Thus, it is possible that a particle-tracking model should have variable lift and drag coefficients that better take into account the estimated instantaneous bubble deformation. The drag coefficient by Haberman and Morton (1953) yielded a trajectory that was closer to the DNS trajectory than when using the drag coefficient given by Clift et al.(1978). It was determined that the lift coefficients given by Dandy and Dwyer (1990) and Auton et al. (1988) yielded capture times that were much bigger than the DNS results and that lift coefficient between the those given by Saffman (1965) and Dandy and Dwyer (1990) would give results that are closer to the DNS results

A NEW SLIP FACTOR CORRELATION FOR CENTRIFUGAL IMPELLERS IN A WIDE RANGE OF FLOW COEFFICIENTS AND PERIPHERAL MACH NUMBERS

ABSTRACT The preliminary design of new centrifugal stages often relies on one-dimensional codes implementing the concept of slip factor. This parameter plays a primary role in the stage design process since it directly affects the calculation of the impeller work coefficient and hence of the components situated downstream. Classical slip factor correlations may not always provide a satisfactory accuracy and generally they fail while attempting at covering a design space in a wide range of flow coefficients and peripheral Mach numbers. In that case the preliminary design has to be refined with more advanced tools, such as computational fluid dynamics (CFD). Often this process needs to be repeated several times before the design cycle ends. In order to predict more effectively the work coefficient as well as to reduce the number of iterations between 1D/CFD codes during the design activity, a new correlation has been developed, which is based on a large number of historical data from both CFD and experimental results. Accurate statistical analyses have shown that slip factor can be strongly linked to significant flow and geometry parameters by means of the outlet deviation angle. As the available calibration dataset gets more and more populated, the presence of specific constants in the structure of the correlation allows the designer to improve the accuracy of predictions

L08: Performance Test of Full-Size Wet Tolerant Compressor

LecturesStandard centrifugal compressors (CC) are designed to process dry gas or gas mixed with negligible amount of liquid Significantliquid content, namely liquid mass fraction (LMF) up to 30%, yield to rapid mechanical deterioration of the CC internals Fieldexperiences have shown significant erosion and corrosion of the compressor internals coupled with intense fouling Furthermore, evena small liquid ingestion is associated with non-negligible CC performance variations; as machine head and efficiency are both affectedtogether with the machine rotordynamics However, the compression of gas containing significant amounts of liquid phase can yield tosome substantial advantages in size and efficiency as liquid removal stations can be reduced (and eventually eliminated) Thus, thecompression station footprint and cost can be reduced accordingly with relevant impact on the layout and cost of subsea stationsMoreover, the introduction of selected wet tolerant features can yield to increased reliability of machines where wet conditions (ormild wet conditions) are triggered during off-design operationsWith the aim of providing a reliable technology for wet gas applications the OEM has developed a full size wet tolerant compressorprototype in which the machine lay-out, material selection, rotordynamics and aerodynamics were specifically designed to processsignificant liquid mass fractions (ie up to 30%)The wet tolerant prototype was tested in a closed loop where rich gas is laden with condensate hydrocarbons and water Thecompressor driven by a 28MW electric VFD motor reaches operating speeds ranging from 8807rpm to 13210rpm A test matrix wasdesigned to explore a wide range of inlet pressures (20bar -110bar) with liquid contents spanning from 5% to 30% of the total massflow rate The compressor performance was measured either with ASME-PTC10 standards (flange-to-flange) and internal dedicatedinstrumentation Moreover, the whole test rig was instrumented and monitored Internal fouling and erosion were investigated withborescope inspections within the test campaign and with bundle removal after the test campaig

EFFECT OF ESTROGEN REPLACEMENT ON BONE METABOLISM AND CYTOKINES IN SURGICAL MENOPAUSE

The effect of oestrogen replacement on bone metabolism and serum cytokine levels (IL1,IL6) was investigated in surgical menopause. The study included 40 female subjects; 10 healthy premenopausal women underwent total hysterectomy without oophorectomy. Thirty healthy premenopausal women underwent total hysterectomy with bilateral oophorectomy. They were randomly divided into 3 groups of 10 subjects. The first group received natural estradiol (0,05 mg/ day) for 6 months; the second group received natural estradiol (0,05 mg/day) and medroxyprogesteron acetate (10 mg/day) for 6 months, the third group received no therapy. Calcium-phosphorus metabolism, inflammatory indices, serum IL1 and IL6 levels were tested before and 6 months after surgery in all patients. A significant increase in serum alkaline phosphatase, urinary cross-links, serum PTH and IL1-IL6 was observed in the untreated women with total hysterectomy and oophorectomy. No significant variation in any of the parameters considered was observed in patients treated with oestrogen, in those treated with oestrogens and medroxyprogesteron nor in patients without oophorectomy. These results in human ''in vivo'' confirm that ovarian steroids play an important role in regulating the production of IL1 and IL6 which could regulate bone resorption