Separation Cascade Research Articles

High voltage formation using the amplifiers cascading method

The dividing of high voltage broadband non-inverting cascade amplifiers into separate cascades, each of which has independent power sources, is suggested. These cascades are connected to one another in series, switching on the operational amplifiers and the feedback links. The gain of each cascade is determined by the non-inverting scheme of feedback that assures accurate signal processing. To provide stable and effective functioning, the operational amplifiers are supplied with power from transistor repeaters. That assures the required feeding voltage levels. Due to the thorough selection of the gain factor and feeding source voltage, the amplifier system achieves the expended output voltage range.

Designing a Squared-Off Cascade for Separation of the 92Mo and 100Mo Isotopes to High Purity

Designing a Squared-Off Cascade for Separation of the 92Mo and 100Mo Isotopes to High Purity

Preparation and hydration mechanism of composite cementitious materials based on iron and steel solid waste

Three groups of composite cementitious materials (CCMs) were prepared by separate grinding, mixed grinding, and cascade grinding using iron and steel solid waste (ISSW) materials (granulated blast furnace slag (GBFS), iron ore tailings (IOTs), steel slag (SS) and desulfurization gypsum (DG)), and the influence on the strength of CCMs was investigated under different water-binder ratios (w/b). Then, the hydration hardening mechanism of the CCMs was revealed via hydration heat analysis, phase composition and structural analysis of hydration products. The results show that the properties of the CCMs prepared by cascade grinding (CGC) is better than that prepared by separate grinding and mixed grinding. When the mass percentage of IOTs and SS in the CGC was 2:3, the mix proportion of CGC is SS+IOTs: GBFS: DG=36:51.5:12.5, mixed with 1.0 % Na2SO4 and 1.2 % Na2SiO3ˑ9 H2O of the CGC, the compressive strength (CS) of mortar sample containing CGC in 28-days and 180-days reach 52.3 MPa and 70.7 MPa respectively under the conditions of standard curing and low water-binder ratios. The hydration degree of pure cement is higher than that of CGC, but types of the hydration products were similar with cement, mainly were Ca(OH)2, iolite, ettringite (AFt) and C-S-H gel. The CGC can greatly reduce the hydration heat of CCMs system in early age, and is suitable for massive concrete structures in which elevated temperature can be kept for a long time.

The Q-cascade Theory with Material Losses and Gains

Material losses and gains are generally unavoidable in isotope separation cascades because of air leakage into the cascade and chemical reactions of the materials in contact with the process gas. Both losses and gains are incorporated into the well-known Q-cascade theory and can be considered differently for each component. The theory is applied, as an example, to investigating the separation of natural uranium to produce low-enriched uranium of 5% 235U, in which UF6 incurs material losses, generating the light impurity hydrogen fluoride (HF). Two approaches are discussed, one using a carrier gas and another purging the light impurity to prevent the light impurity from exceeding the upper limit in the cascade product end for safe cascade operation. The results show that using carrier gas increases the relative total flow of the cascade, whereas purging the light impurity requires the development of a purging technology. The investigation presents a complicated but real practical scenario, where the components of different physical and chemical properties (some with and without material losses, and some with gains) all appear in the process gas, and demonstrates the applicability of the theory in the study of separation cascades.

Advancements in numerical modeling of ideal multicomponent isotope separation Cascades: A comparative study

The complexity of operational conditions in stable isotope separation cascades necessitates the utilization of numerical methods for cascade design and performance analysis. This study focuses on solving a system of nonlinear algebraic equations derived from the mass and energy balance equations, which is a fundamental challenge in analyzing and designing cascades and developing numerical methods. Two existing numerical algorithms were selected from the literature and modified for quasi-ideal cascade systems. The performance of these algorithms was examined and compared, with a particular emphasis on influential parameters such as the number of stages, the number of isotopes, and the separation factor. The first algorithm solves the concentration and flow equations separately, while the second algorithm solves all equations simultaneously. The results indicate that the first algorithm exhibits significant superiority over the second algorithm. In most cases, the second algorithm either fails to converge or exhibits a slower convergence speed. Additionally, the results demonstrate that increasing the number of stages impacts the convergence time, while an increase in the separation factor leads to greater convergence complexity.

Optimization of multicomponent isotopes separation cascades parameters using improved grey wolf optimizer algorithm

The number of variables and design parameters in the multicomponent isotope separation cascades is considerable, and it is highly challenging to choose the best arrangement by obtaining the minimum interstage flow rate. Therefore, it is very important to develop a computational tool with high capability for calculating the cascade optimal parameters. The Improved Grey Wolf Algorithm, IGWO, is used in this study to develop an efficient code called the Isotopic Separation Real Code (ISRC-IGWO), which calculates the optimum parameters in the cascade for the separation of multicomponent mixtures. Investigations have been conducted in 4 separate tests to demonstrate this code's capability for computing the parameters with values close to the optimal conditions (in convergence to the near-optimal cascade). These evaluations have been carried out for both square and taper cascades, and different objective functions have been included in all tests. The findings show that ISRC-IGWO results are in agreement with optimal parameters calculation using other existing methods and IGWO is able to calculate cascade optimal parameters.

Optimization of isotopic binary and multi-component separation cascades using a novel nature-inspired horse herd algorithm

ABSTRACT The gas centrifuge process is widely used in the world to separate binary and multi component mixtures of isotopes. The majority of a plant cost is related to the number of centrifuges in a cascade. The cascade should be built so that it uses the fewest possible centrifuges for a given product and waste concentrations. Minimizing the number of centrifuges and the total flow rates, is a key point in designing and optimizing isotope separation cascades. The main purpose of this paper is to present a novel swarm intelligence based algorithm to solve these kinds of problems. This novel algorithm, called the Horse Herd Optimization Algorithm (HOA), is inspired by the behavioral patterns of horses in their habitats. In this work, it is demonstrated that the suggested algorithm can solve complicated multidimensional problems. HOA is tested by some test functions of high-dimensions and the results are compared with the strongest available optimization algorithms. In next, the proposed algorithm is used to optimize gas centrifuge cascades for the separation of binary and multicomponent mixtures of isotopes in several cases. Also, ideal and optimum cascades are compared in different separating regimes of the stages, using this method. Considering the performance of HOA in solving multidimensional problems, this algorithm is proposed for the optimization of long cascades.

Profiling extracellular vesicle surface proteins with 10 µL peripheral plasma within 4h.

Extracellular vesicle (EV) surface proteins, expressed by primary tumours, are important biomarkers for early cancer diagnosis. However, the detection of these EV proteins is complicated by their low abundance and interference from non-EV components in clinical samples. Herein, we present a MEmbrane-Specific Separation and two-step Cascade AmpLificatioN (MESS2CAN) strategy for direct detection of EV surface proteins within 4h. MESS2CAN utilises novel lipid probes (long chains linked by PEG2K with biotin at one end, and DSPE at the other end) and streptavidin-coated magnetic beads, permitting a 49.6% EV recovery rate within 1h. A dual amplification strategy with a primer exchange reaction (PER) cascaded by the Cas12a system then allows sensitive detection of the target protein at 10 EV particles per microliter. Using 4 cell lines and 90 clinical test samples, we demonstrate MESS2CAN for analysing HER2, EpCAM and EGFR expression on EVs derived from cells and patient plasma. MESS2CAN reports the desired specificity and sensitivity of EGFR (AUC=0.98) and of HER2 (AUC=1) for discriminating between HER2-positive breast cancer, triple-negative breast cancer and healthy donors. MESS2CAN is a pioneering method for highly sensitive in vitro EV diagnostics, applicable to clinical samples with trace amounts of EVs.

Quasi-three-dimensional loss prediction model of subsonic compressor cascade based on bidirectional long short-term memory networks and multi-head self-attention

The prediction of compressor cascade loss is a crucial aspect of compressor design. Flow separation is an important flow structure and the main source of loss in subsonic cascades. In order to capture the flow separation and accurately evaluate flow loss, a data-driven quasi-three-dimensional (quasi-3D) subsonic compressor cascade loss prediction model based on bidirectional long short-term memory (BiLSTM) and multi-head self-attention is proposed. The model contains four sub-models to predict the pressure, temperature, axial velocity, and total pressure loss coefficient in two-dimensional slices along the axial direction, using Mach number, curved blade angle, solidity, camber angle, and incidence as inputs, respectively. For the purpose of adapting to cascade geometrical change, geometric reformulation is adopted before the model training. The model is trained and tested by validated computational fluid dynamics results, which contain symmetric separation and asymmetric separation samples. It is proved that the model is able to accurately predict flow parameters value in each slice. Then, four typical cases are mainly discussed, which shows that the model can effectively capture the characteristics of flow separation formation and development. Afterward, different models are compared, and it is found that the BiLSTM with multi-head self-attention model achieved the lowest mean squared error, which is because of its outstanding predicting ability in asymmetric separation cases. The work of this paper indicates that the quasi-3D loss prediction model proposed in this paper will be beneficial to the flow separation structure rapid prediction and cascade loss accurate evaluation in compressor design.

Development of schemes from a single cascade to multi-cascades for separation of regenerated uranium

Returning precious fissile materials containing 235U, obtained from regenerated uranium, to the nuclear fuel cycle is important for the production of sustainable nuclear energy. Herein, starting from the basic single cascade separation scheme, schemes for enriching regenerated uranium are developed to satisfy the requirements for low-enriched uranium with a commercial grade and several supplementary separation conditions to the greatest extent for different considerations involving the consumption of natural uranium, scale of separation cascade, and material recovery. Double- and triple-cascade schemes are derived from the consideration of improving the basic scheme by eliminating its drawbacks such as the contamination of the entire cascade by artificial nuclides. All schemes are optimized based on a Q-model cascade and are compared. The results demonstrate that the triple-cascade scheme exhibits a good separation performance and may be a good choice among the existing schemes. However, the concentration of 235U in this scheme exceeds the limitation specified by the international standard for handling fissile materials; therefore, this scheme requires further improvement.

Remote Monitoring the Parameters of Interest in the 18O Isotope Separation Technological Process

This manuscript presents the remote monitoring of the main parameters in the 18O isotope separation technological process. It proposes to monitor the operation of the five cracking reactors in the isotope production system, respectively, the temperature in the preheating furnaces, the converter reactors and the cracking reactors. In addition, it performs the monitoring of the two separation columns from the separation cascade structure, respectively, the concentrations of the produced 18O isotope and the input nitric oxides flows. Even if the production process is continuously monitored by teams of operators, the professionals who designed the technical process and those who can monitor it remotely have the possibility to intervene with the view of making the necessary adjustments. Based on the processing of experimental data, which was gathered from the actual plant, the proposed original model of the separation cascade functioning was developed. The process computer from the monitoring system structure runs the proposed mathematical model in parallel with the real plant and estimates several signal values, which are essential to be known by the operators in order to make the appropriate decisions regarding the plant operation. The separation process associated with the final separation column from the separation cascade structure is modeled as a fractional-order process with variable and adjustable differentiation order, which represents another original aspect. Neural networks have been employed in order to implement the proposed mathematical model. The accuracy, validity and efficiency in the operation of the proposed mathematical model is demonstrated through the simulation results presented in the final part of the manuscript.

A HD-ZIP transcription factor specifies fates of multicellular trichomes via dosage-dependent mechanisms in tomato.

Hair-like structures are shared by most living organisms. The hairs on plant surfaces, commonly referred to as trichomes, form diverse types to sense and protect against various stresses. However, it is unclear how trichomes differentiate into highly variable forms. Here, we show that a homeodomain leucine zipper (HD-ZIP) transcription factor named Woolly controls the fates of distinct trichomes in tomato via a dosage-dependent mechanism. The autocatalytic reinforcement of Woolly is counteracted by an autoregulatory negative feedback loop, creating a circuit with a high or low Woolly level. This biases the transcriptional activation of separate antagonistic cascades that lead to different trichome types. Our results identify the developmental switch of trichome formation and provide mechanistic insights into the progressive fate specification in plants, as well as a path to enhancing plant stress resistance and the production of beneficial chemicals.

Vortex separation cascades in simulations of the planar flow past an impulsively started cylinder up to

Direct numerical simulations of the flow past an impulsively started cylinder at high Reynolds numbers (25k–100k) reveal an intriguing portrait of unsteady separation. Vorticity generation and vortex shedding entails a cascade of separation events on the cylinder surface that are reminiscent of Kelvin–Helmholtz instabilities. Primary vortices roll up along the cylinder surface as a result of instabilities of the initially attached vortex sheets, followed by vortex eruptions, creation of secondary vorticity and formation of dipole structures that are subsequently ejected from the surface of the cylinder. We analyse the vortical structures and their relationship to the forces experienced by the cylinder. This striking cascade of vortex instabilities may serve as reference for reduced-order models of flow separation and as guide for flow control of separated flows at high Reynolds numbers.

Study on the operating conditions of centrifuges and their individual separative power in a stage of an isotope separation cascade

Since the ideal cascade theory, several mathematical models have been developed to improve the understanding of isotopic separation cascades. Despite numerous advances in modeling multicomponent and transient cascades, there has not yet been a model that takes into account the individual centrifuges' operating conditions and separative power.This study analyses how the number of centrifuges in a stage relates to the pressure drop in the pipes, which in turn affects the centrifuges’ separative power. It estimates the local operating conditions, checks them against the mass balances in the pipes and, then, calculates the separative performance of the centrifuges.Results were presented for a stage with 40 generic centrifuges. There was a sharp pressure drop in the extremities of the stage that caused roughly 15% and 30% pressure loss in the feed and product pipes, respectively, which caused the last centrifuge to yield a separative power 14% lower than the first one.

Piecing Complement Together with LEGO Bricks: Impacts on Interest, Confidence, and Learning in the Immunology Classroom.

Teaching and learning complex molecular cascades can often be challenging. In immunology, students struggle to visualize immunological processes, such as activation of the complement system, which involves three separate cascades leading to multiple effector functions. Offering learning activities that use tangible modeling can help students learn conceptually difficult content by fostering a visual understanding of concepts, as well as instill confidence and interest in the material. In this article, we describe a learning activity using LEGO bricks that demonstrates the activation of the classical, lectin, and alternative complement pathways and formation of the membrane attack complex. In both an introductory and advanced immunology course, we investigated the effect of the activity on student learning and subject confidence. Performance on examination questions about complement demonstrated that the LEGO activity improved learning in a naive student population (students in introductory immunology), but not in a previously informed student population (students in advanced immunology). In addition, self-reported confidence in the content was significantly higher in students who completed the LEGO activity in the advanced course, but not the introductory course, compared with those who did not do the activity. Students in both courses who did the activity had a positive perception of the activity, with a majority of students reporting that they enjoyed the activity and had more interest in the complement system.

Numerical simulation of hydrodynamic performance of taper cascades in transient conditions

The hydrodynamic performance of separation cascades involves determining the distribution of pressure and flow along cascades which are important from the design and operational point of view. In this paper, numerical simulation of hydrodynamic performance of taper cascades in the transient state is presented. This mathematical modeling consisted of a set of hyperbolic partial, ordinary differential and algebraic equations of transient flow in a complex pipe network. In order to achieve this goal, a MATLAB code, named Hydrodynamic Simulation of Separation Cascades (HSSC), has been developed. This code calculates the flow and pressure distribution within the cascade components such as pipes, control valves, tanks and gas centrifuges (GC). Using this code, the results of transient hydrodynamic simulations for a taper cascade with 4 stages and 8 GCs are presented wherein the working gas is xenon, and for different operational conditions, analysis is performed on the equilibrium time and gas holdup.

Optimal design of separation cascades using the whale optimization algorithm

High-fidelity simulation tools are required to treat isotope separation cascades. In the present work, a multi-objective optimization method based on Whale Optimization Algorithm, WOA, is developed to obtain the optimal parameters of recycling cascades for separating the binary mixture of isotopes. Detail treatment and simulation of isotope separation phenomena are critical in the economic aspect. The WOA is a novel meta-heuristic algorithm which imitates the bubble-net hunting strategy used by humpback whales in looking for food. In this analysis, the WOA is implemented for benchmark functions and its capabilities demonstrated; in the next step, it is enforced for main real problems such as isotope separation cascades to minimize the total number of centrifuges and flow rates in the process. The optimization results are evaluated against other well-known schemes. It is revealed the outcomes of WOA are in good agreement with those obtained by the conventional methods.

Accumulation of Isotope Mixture Components in a Separation Cascade

Accumulation of Isotope Mixture Components in a Separation Cascade

Recovery of bio-based medium-chain fatty acids with membrane filtration

Medium-chain fatty acids (MCFAs) are promising platform chemicals for biorefineries in the circular economy. An efficient and sustainable process for their recovery from biomass, however, remains elusive. This work aimed to develop a separation cascade for MCFA recovery from fermentation broth (FB) using membrane filtration. This technical-scale process consisted of a filter-press, thermal-pretreatment, ultrafiltration (UF), and nanofiltration (NF). While solid–liquid separation and UF were efficient, NF fluxes declined rapidly due to membrane fouling, limiting MCFA separation and concentration. Thermal pretreatment and UF membrane pore size had a negligible effect on filtration performance and diafiltration trials in NF proved ineffective. While process feasibility is presently constrained by membrane fouling in NF, characterization, and reduction of foulants could make the process readily viable. Overall, the membrane filtration cascade yielded a product, the NF retentate, with an MCFA concentration approximately 230% greater than that of the feedstock with an average overall recovery of 84%. Furthermore, although the concentration of MCFAs (C4-C8, 12.9 gL–1) may be inadequate for direct use, this product, being clarified and enriched, could serve as an improved feedstock for MCFA purification by alternative methods.

Optimization Criterion for Two-Stage Cascade for Iterative Molybdenum Isotopes Recovery by the method of laser-assisted retardation of condensation(SILARC)

In this paper, application of the method of laser-assisted retardation of condensation has been considered for molybdenum isotope separation. Enrichment factor as a function of pressure and temperature of gas flow cold core have been evaluated. Since the maximal value of enrichment factor is not high(~ 1.8), to achieve desired enrichment level in products an iterative procedure is applied. To reduce the amount of wastes and increase performance of the SILARC method, introduction of the second stage into the separation cascade is considered. Relations between molar and isotopic fractions of target isotopologues on the first and second stages of the cascade at each iteration are found. Optimization problem is formulated to evaluate optimal physical parameters of a two-stage cascade for molybdenum isotopes enrichment.