Multi-stage Mode Research Articles

A Statistical Characterization of the Effects of Mistuning in Multistage Bladed Disks

A great deal of research has been conducted on the effects of small random variations in structural properties, known as mistuning, in single stage bladed disks. Due to the inherent randomness of mistuning and the large dimensionality of the models of industrial bladed disks, a reduced order modeling approach is required to understand the effects of mistuning on a particular bladed disk design. Component mode mistuning (CMM) is an efficient compact reduced order modeling method that was developed to handle this challenge in single stage bladed disks. In general, there are multiple stages in bladed disk assemblies, and it has been demonstrated that for certain frequency ranges accurate modeling of the entire bladed disk assembly is required because multistage modes exist. In this work, a statistical characterization of structural mistuning in multistage bladed disks is carried out. The results were obtained using CMM combined with a multistage modeling approach previously developed. In addition to the statistical characterization, a new efficient classification method is detailed for characterizing the properties of a mode. Also, the effects of structural mistuning on the characterization of the mode is explored.

Software tool for mining liquid chromatography/multi‐stage mass spectrometry data for comprehensive glycerophospholipid profiling

Electrospray ionization mass spectrometry (ESI-MS) has emerged as an indispensable tool in the field of lipidomics. Despite the growing interest in lipid analysis, there are only a few software tools available for data evaluation, as compared for example to proteomics applications. This makes comprehensive lipid analysis a complex challenge. Thus, a computational tool for harnessing the raw data from liquid chromatography/mass spectrometry (LC/MS) experiments was developed in this study and is available from the authors on request. The Profiler-Merger-Viewer tool is a software package for automatic processing of raw-data from data-dependent experiments, measured by high-performance liquid chromatography hyphenated to electrospray ionization hybrid linear ion trap Fourier transform mass spectrometry (FTICR-MS and Orbitrap) in single and multi-stage mode. The software contains three parts: processing of the raw data by Profiler for lipid identification, summarizing of replicate measurements by Merger and visualization of all relevant data (chromatograms as well as mass spectra) for validation of the results by Viewer. The tool is easily accessible, since it is implemented in Java and uses Microsoft Excel (XLS) as output format. The motivation was to develop a tool which supports and accelerates the manual data evaluation (identification and relative quantification) significantly but does not make a complete data analysis within a black-box system. The software's mode of operation, usage and options will be demonstrated on the basis of a lipid extract of baker's yeast (S. cerevisiae). In this study, we focused on three important representatives of lipids: glycerophospholipids, lyso-glycerophospholipids and free fatty acids.

Design of Hybrid Drying- Dedusting Unit Processor for Rough Rice Processing

Advanced drying technology enables drying of rough rice and dedusting of rice husks to be carried out simultaneously in the same unit processor. This paper reports the efficiency of dedusting of rice husks in a two-stage inclined cross flow fluidized bed dryer and the drying kinetics of rough rice in a batch fluidized bed dryer as well as the conceptual design of a hybrid drying – dedusting unit processor. Experimental works had been carried out using rough rice (a Group D particle according to Geldart classification of powders) in a 2.5 m height two-stage inclined fluidized bed column of cross sectional area of 0.61m x 0.15m and a 3 m high batch fluidized bed dryer. The objectives of the study was to investigate the separation efficiency of dedusting of rice husks in the two-stage cross flow fluidized bed dryer and to study the drying kinetics of rough rice drying in the batch fluidized bed dryer. The experimental results showed that the dedusting separation efficiency at low superficial gas velocity gave unsatisfactory separation of merely 40% of rice husks. At higher superficial gas velocity, separation efficiency of rice husks as high as 93% was achieved. In addition, higher distributor inclination angle gave slightly improved separation efficiency. The drying kinetics showed that the residence time that is required to reduce the moisture content of rough rice to 18% (intermediate storage moisture content for second stage drying) is 3 minutes whereas the residence time that is required to reduce the moisture content to 13% (desirable final moisture content) is approximately 10 minutes regardless of the effect of kernel cracking. It was also found that higher drying temperatures gave higher drying rate. A conceptual design has been developed based on the results obtained in the studies. In order to maximize the heat utilization and to carry out two processes viz. dedusting and drying in one unit processor, it is suggested that drying – dedusting can be carried out in a multistage mode where drying is taken place at each stage while dedusting is taking place at the upper stage. This concept can be applied to a packed bed or a fluidized bed unit processor.

On the use of colloid-enhanced ultrafiltration in view of enantiomeric enrichments and limiting conditions

We review here the different techniques which have been used during the past twenty years to achieve enantiomer separation, distinguishing between analytical and preparative methods, and stressing upon the place of techniques based on surfactants and colloidal particles. Due to the great progress of membrane technologies, special emphasis will be put on the different attempts resting on the use of ultrafiltration techniques. The main successes in enantiomer separations (or at least enantiomer enrichment) obtained with these techniques involved the formation of a ternary complex including a metal ion (Cu2+ in most cases). Our concern in this work was to investigate the feasibility of performing enantiomer enrichments through micellar ultrafiltration, when only weak enantiomer/selector complexes were formed, not requiring a bridging metal ion. A model system (ephedrine enantiomers and (S)-dodecoxycarbonylvaline micelles as chiral selector), for which successful separations were achieved in micellar electrokinetic chromatography, was tested for this purpose. The lack of significant enrichment tend to demonstrate, that, in such a case, the difference in the binding of the enantiomers to the chiral selector (measured from UV spectroscopy and circular dichroism) is too weak to think about an application of ultrafiltration techniques, even in a multistage mode.

Structural Investigation on Water-Induced Phase Transitions of Poly(ethylene imine). 1. Time-Resolved Infrared Spectral Measurements in the Hydration Process

Time-resolved infrared spectral measurements were made successfully for studying the microscopic mechanism of water-induced solid-state phase transitions of poly(ethylene imine) (PEI) in the hydration process at room temperature. The initial sample, obtained by cooling the melt under a dry atmosphere, showed the infrared spectra characteristic of the anhydrate phase consisting of doubly stranded helices. When this sample was exposed into an atmosphere of 100% relative humidity, the infrared spectra were found to change in a multistage mode from anhydrate to hemihydrate (molar ratio of ethylene imine unit/water = 1/0.5) to sesquihydrate (1/1.5) and to dihydrate (1/2), where the molecular chains in the latter three phases take the planar-zigzag all-trans conformation and form the complexes with water through the hydrogen bonds. The spectral measurements were made also for heavy water (D2O) as well as light water (H2O), and the quantitative analysis could be made more successfully for the former case, because the overlap of the polymer bands with water bands could be avoided due to the shift of the broad absorption bands of water molecules. A comparison was made for the strength of hydrogen bonds between PEI and PEI, PEI and water, and water and water. The infrared bands characteristic of the amorphous region could be detected in the frequency region of 1800−2500 cm-1, the intensities of which were found to decrease in parallel to the crystal phase transition, indicating that some parts of the amorphous region can also crystallize into the hydrates in the hydration process.

Multistage electrophoresis system for the separation of cells, particles and solutes.

It is common to operate equilibrium-based separation methods, such as distillation and extraction, as multistage unit operations, in which equilibrium is presumably achieved within each stage. Two rate-based separation processes, free electrophoresis and magnetic particle separation, have now been operated in multistage mode. Preparative free electrophoresis of particles and solutes has resisted scale-up and is confined to a narrow range of ionic compositions. Natural convection induced in electrophoresis buffers by Ohmic heating has been a strong deterrent and has led to such measures as radial electrophoresis in Couette flow, free-flow electrophoresis, low-gravity electrophoresis, density gradient electrophoresis, and reorienting density gradient electrophoresis, to name a few. The short vertical electrophoresis path exploited in the last-mentioned forms the basis for multistage electrophoresis. A thin-layer countercurrent distribution apparatus was designed and constructed so that up to 20 fractions could be collected on the basis of electrophoretic mobility by applying an electric field. The mixture to be separated starts in a bottom cavity, and successive top cavities collect fractions as separand particles or molecules are electrophoresed upward out of the bottom cavity. Mathematical models of this process were developed, and experiments were performed to verify the predictions of the models by collecting and counting particles in each cavity after fractionation.