Shortcut Procedure Research Articles

Cyclic stress–strain behavior of additively manufactured gamma prime strengthened superalloy at elevated temperatures

The γ́-precipitation hardened nickel-based superalloy IN939 manufactured by laser powder bed fusion (L-PBF) was subjected to cyclic loading to determine the cyclic stress–strain curve by short-cut procedure. The effect of building on loading direction/orientation was investigated. 〈001〉 crystallographic texture along the building direction was observed. The cyclic stress–strain curves were measured at 800 °C and 900 °C and the differences in cyclic plasticity were revealed. The specimens prepared by L-PBF with a building direction parallel to the loading axis exhibited the highest cumulative plastic deformation at both temperatures, while L-PBF with a building direction perpendicular to the loading axis was the lowest. Elastic moduli were determined and the differences were attributed to the crystallographic texture. In addition, conventionally cast IN939 was investigated as the reference material. Minor microstructural changes due to cyclic straining were inspected by transmission electron microscopy.

Closed testing with Globaltest, with application in metabolomics.

The Globaltest is a powerful test for the global null hypothesis that there is no association between a group of features and a response of interest, which is popular in pathway testing in metabolomics. Evaluating multiple feature sets, however, requires multiple testing correction. In this paper, we propose a multiple testing method, based on closed testing, specifically designed for the Globaltest. The proposed method controls the familywise error rate simultaneously over all possible feature sets, and therefore allows post hoc inference, that is, the researcher may choose feature sets of interest after seeing the data without jeopardizing error control. To circumvent the exponential computation time of closed testing, we derive a novel shortcut that allows exact closed testing to be performed on the scale of metabolomics data. An R package ctgt is available on comprehensive R archive network for the implementation of the shortcut procedure, with applications on several real metabolomics dataexamples.

How to reach optimal estimates of confidence intervals in microscopic counting of phytoplankton?

Present practices in the microscopic counting of phytoplankton to estimate the reliability of results rely on the assumption of a random distribution of taxa in sample preparations. In contrast to that and in agreement with the literature, we show that aggregated distribution is common and can lead to over-optimistic confidence intervals, if estimated according to the shortcut procedure of Lund et al. based on the number of counted cells. We found a good linear correlation between the distribution independent confidence intervals for medians and those for parametric statistics so that 95% confidence intervals can be approximated by using a correction factor of 1.4. Instead, the recommendation to estimate confidence intervals from the total number of counted cells according to Lund et al. should be categorically rejected. We further propose the adoption of real-time confidence intervals during microscopic counting as the criterion to define how long counting should be continued. Then each sample can be counted in its individual way to reach the necessary reliability independent of highly different samples. Such a dynamic counting strategy would be the most significant development in the quality control of phytoplankton counting since the early pioneers established the present counting practices in the late 1950s.

Functional Comparison of Blood-Derived Human Neural Progenitor Cells.

Induced pluripotent stem cell (iPSC)-derived neural progenitor cells (NPCs) are promising tools to model complex neurological or psychiatric diseases, including schizophrenia. Multiple studies have compared patient-derived and healthy control NPCs derived from iPSCs in order to investigate cellular phenotypes of this disease, although the establishment, stabilization, and directed differentiation of iPSC lines are rather expensive and time-demanding. However, interrupted reprogramming by omitting the stabilization of iPSCs may allow for the generation of a plastic stage of the cells and thus provide a shortcut to derive NPSCs directly from tissue samples. Here, we demonstrate a method to generate shortcut NPCs (sNPCs) from blood mononuclear cells and present a detailed comparison of these sNPCs with NPCs obtained from the same blood samples through stable iPSC clones and a subsequent neural differentiation (classical NPCs—cNPCs). Peripheral blood cells were obtained from a schizophrenia patient and his two healthy parents (a case–parent trio), while a further umbilical cord blood sample was obtained from the cord of a healthy new-born. The expression of stage-specific markers in sNPCs and cNPCs were compared both at the protein and RNA levels. We also performed functional tests to investigate Wnt and glutamate signaling and the oxidative stress, as these pathways have been suggested to play important roles in the pathophysiology of schizophrenia. We found similar responses in the two types of NPCs, suggesting that the shortcut procedure provides sNPCs, allowing an efficient screening of disease-related phenotypes.

Drawing PT-phase envelopes and calculating critical points for multicomponent systems using flash calculations

Objectives. This study aims to draw PT-phase envelopes and calculate the critical points for multicomponent systems using flash calculations.Methods. Flash calculations with an equation of state and a mixing rule were used to construct phase envelopes for multicomponent systems. In general, the methodology uses the Soave–RedlichKwong equation of state and Van der Waals mixing rules; and the Peng–Robinson equation of state with Wong–Sandler mixing rules and the non-random two-liquid activity coefficient model.Results. The method was applied to the following mixtures: ethane (1)–butane (2) (four different compositions); ethane (1)–propane (2) (four different compositions); butane (1)–carbon dioxide (2) (three different compositions); C2C3C4C5C6 (one composition); isobutane–methanol–methyl tertbutyl ether–1-butene (one composition); and propylene–water–isopropyl alcohol–diisopropyl ether (one composition).Conclusions. Our results agreed to a large extent with the experimental data available in the literature. For mixtures that contained CO2 , the best results were obtained using the PengRobinson equation of state and the Wong–Sandler mixing rules. Our methodology, based on flash calculations, equations of state, and mixing rules, may be viewed as a shortcut procedure for drawing phase envelopes and estimating critical points of multicomponent systems.

A simplified and general approach to absorption and stripping with parallel streams

Abstract This work presents a simplified and general approach for calculating the number of ideal stages and the corresponding concentrations in absorption and stripping with parallel streams. Vapor (gas)/liquid separation processes with parallel streams involve the division of either the vapor phase or the liquid phase in a selected and feasible number of sub-streams and their contact, in alternate trays, with the entire stream of the other phase, i.e. the liquid or vapor phases, respectively. The division of the vapor phase (para-absorption or stripping) allows the possible allocation of a larger number of trays in the same column height and can be an alternative for processes conducted under low pressure and/or involving thermosensitive compounds. On the other hand, the partition of the liquid phase (meta-absorption or stripping) permits a better liquid phase flowing, especially in the case of large liquid loads. The mass balance equations are formulated for mixtures with a unique component being transferred and for two or more partitions of the vapor or liquid phases. Based on the obtained operation lines, the proposed approach allows the calculation of the number of ideal stages for para- and meta-absorption/stripping with any integer number of divisions of the corresponding stream. Furthermore, the additional assumption of a linear equilibrium behavior makes possible the formulation of recurrence equations representing the change of the vapor (para-separation) or liquid (meta-separation) concentrations along the column. In fact, a linear β th -order difference equation, with β corresponding to the number of divisions of the selected stream, can be formulated in each case and the exact solutions for β equal to 2, 3 and 4 are presented. The approach was tested in the calculation of para- and meta-absorption/stripping columns of two different mixtures of interest for bio-refineries, namely those mixtures related to the recovery of bioethanol lost during sugar fermentation and to the desorption of free fatty acids from vegetable oils. Based on the calculated results, the advantages of absorption/stripping with parallel streams are discussed. The new approach can be used as a reliable shortcut procedure in the optimization and intensification of complex chemical processes involving absorption and/or stripping steps, as well as a learning tool for teaching the design of downstream equipment.

A shortcut procedure for calculation of process side heat duty of refinery fired heaters

Absorbed heat duty of process side of a fired heater often requires rigorous vapor–liquid equilibrium calculations and is usually performed with costly process simulator software. An alternative, shortcut method is proposed, which may be easily and efficiently implemented in a spreadsheet. The results of the proposed procedure were checked against those of a process simulator and against the results of the indirect efficiency calculation method, for three different existing refinery furnaces. The accuracy of the proposed method was found comparable to both the others.

Simple multicomponent batch distillation procedure with a variable reflux policy

This paper describes a shortcut procedure for batch distillation simulation with a variable reflux policy. The procedure starts from a shortcut method developed by Sundaram and Evans in 1993 and uses an iterative cycle to calculate the reflux ratio at each moment. The functional relationship between the concentrations at the bottom and the dome is evaluated using the Fenske equation and is complemented with the equations proposed by Underwood and Gilliland. The results of this procedure are consistent with those obtained using a fast method widely validated in the relevant literature.

Analytical design of proportional-integral controllers for the optimal control of first-order processes with operational constraints

A novel analytical design method of industrial proportional-integral (PI) controllers was developed for the optimal control of first-order processes with operational constraints. The control objective was to minimize a weighted sum of the controlled variable error and the rate of change in the manipulated variable under the maximum allowable limits in the controlled variable, manipulated variable and the rate of change in the manipulated variable. The constrained optimal servo control problem was converted to an unconstrained optimization to obtain an analytical tuning formula. A practical shortcut procedure for obtaining optimal PI parameters was provided based on graphical analysis of global optimality. The proposed PI controller was found to guarantee global optimum and deal explicitly with the three important operational constraints.

Analysis of the Effective and Internal Cyclic Stress Components in the Inconel Superalloy Fatigued at Elevated Temperature

Cyclic multiple step test in strain control have been performed on cylindrical specimens of cast polycrystalline Inconel 738LC and 792-5A superalloys at 800 °C in laboratory atmosphere. Hysteresis loops were analyzed according to the statistical theory of hysteresis loop. The effective and internal stress components were evaluated. The effective stress of γ´ precipitate has significant influence on the stress-strain response both materials. The stress amplitude in IN 792-5A is higher than in IN 738LC at approximately same total strain amplitude due to significantly higher effective stress of γ´ phase. Cyclic hardening/softening curves and cyclic stress-strain curves using short-cut procedure were obtained. Cyclic hardening/softening behavior depends both on temperature and strain amplitude. Low amplitude straining is characterized by the saturation of the stress amplitude. In high amplitude straining slight softening was found. The cyclic stress-strain curves for both materials can be fitted by power law. Cyclic stress-strain response in terms of internal and effective stress components is discussed in relation to microstructural parameters of the materials. The observation of surface relief revealed the presence of persistent slip markings.

Effect of Temperature on the Cyclic Stress Components of Gamma - TiAl Based Alloy with Niobium Alloying

Cyclic strain controlled multiple step tests have been performed on cylindrical specimens of cast -TiAl based alloy with 2 at.% of Nb with nearly lamellar microstructure at 23 and 750 °C in laboratory atmosphere with the aim to study the effect of temperature on the internal and effective cyclic stress components. At these temperatures, the evolution of the effective and internal stress components and the effective elastic moduli were derived from the hysteresis loops analyzed according to the statistical theory of hysteresis loop. Cyclic hardening/softening curves and cyclic stress-strain curves were obtained at both temperatures. Cyclic stress–strain curves measured using short-cut procedure coincide with the basic cyclic stress-strain curve. They are shifted to lower stresses with increasing temperature. Cyclic stress-strain response at both temperatures was compared and discussed in relation to changes of internal and effective stress components and dislocation modes referred in literature concerning this class of the material.

Optimum design of composite laminates for frequency constraints

Abstract A method for minimum thickness multilayer rectangular composite laminates is presented which is based on a layerwise optimization procedure under natural frequency limitations. In this method, all types of boundary conditions and their combinations can be taken into account. Analysis is based on the Ritz approximations, and no limitations exist on the number of layers that can be considered or the plate’s aspect ratio. Coupling of flexural and torsional stiffness terms need not be zero in any of the cases. Optimization constraints can be either limits on the fundamental frequency or separation between two natural frequencies. Hybrid combination of layers is also made possible in order to enhance the laminate economy, and a short cut procedure is recommended to save total computational efforts. Examples are offered that illustrate the method’s capabilities, and the results are verified by comparison to some published ones.

LARGE DISTAL VAGINAL APLASIA WITH HAEMATO-COLPOS AND HAEMATOMETRA; RESTORATION OF REPRODUCTIVE TRACT CONTINUITY IS A CHALLENGE FOR GYNAECOLOGISTS: A CASE REPORT

Distal vaginal aplasia and functional uterus is an uncommon congenital malformation. Reconstructive therapy is controversial. Mental problems may result. The objective in this case was to restore menstruation, and preserve reproductive performance by avoiding hysterectomy, in order to prevent psychological impacts of amenorrhoea and sterility. This case is a 14 years old girl presented with classical features of vaginal obstruction and functional uterus. Physical examination revealed absent vagina and a pelvic mass. The patient and her family were very concerned about menstruation and fertility. Neovagina was constructed successfully using the modified McIndoe vaginoplasty. Eventually abdominal Vagino-neovaginal anastomosis was necessary to restore reproductive tract continuity. The outcome was restoration of menstruation and made future marriage and fertility more actual. This required six surgical interventions over a period of ten months. Associated pelvic endometriosis was observed and right salpingectomy was thought necessary. Although hysterectomy is a shortcut procedure to relieve complications of menstrual retention in vaginal obstruction, it will cause psychological trauma to the patient and her family. Construction of artificial vagina and Vagino-neovaginal anastomosis can be successfully performed to provide the patient an opportunity for conservative management, resulting in menstruation, and some potential for fertility.

An Improved Short-Cut Method for Effectiveness Factor Estimation

Two main short-cut methods for catalyst particle effectiveness factor (EF) estimation that use kinetics linearization about surface and average concentration conditions have been recently considered in the literature. The former produces simple computations with acceptable estimations for low Thiele modulus values, although negative particle concentrations can be generated. The latter is intended to improve the particle concentration profiles but at the expense of increased computations. The aim of this paper is to propose a hybrid method that combines the advantages of the two approaches to obtain EF and concentration profile estimations that are better than those of the individual ones. This is done by taking a kinetics linearization at an artificial concentration condition resulting from a type of Crank−Nicholson scheme. From a simple error analysis, it is shown that the resulting short-cut procedure displays enhanced convergence properties, which is corroborated by means of numerical computations.

Power and cost aware localized routing with guaranteed delivery in unit graph based ad hoc networks

AbstractIn a localized routing algorithm, each node currently holding a message makes forwarding decision solely based on the position information about itself, its neighbors and destination. In a unit graph, two nodes can communicate if and only if the distance between them is no more than the transmission radius, which is the same for each node. This paper proposes localized routing algorithms, aimed at minimizing total power for routing a message or maximizing the total number of routing tasks that a network can perform before a partition. The algorithms are combinations of known greedy power and/or cost aware localized routing algorithms and an algorithm that guarantees delivery. A shortcut procedure is introduced in later algorithm to enhance its performance. Another improvement is to restrict the routing to nodes in a dominating set. These improvements require two‐hop knowledge at each node. The efficiency of proposed algorithms is verified experimentally by comparing their power savings, and the number of routing tasks a network can perform before a node loses all its energy, with the corresponding shortest weighted path algorithms and localized algorithms that use fixed transmission power at each node. Significant energy savings are obtained, and feasibility of applying power and cost‐aware localized schemes is demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.

Internal Node and Shortcut Based Routing with Guaranteed Delivery in Wireless Networks

Several localized position based routing algorithms for wireless networks were described recently. In greedy routing algorithm (that has close performance to the shortest path algorithm, if successful), sender or node i>S currently holding the message i>m forwards i>m to one of its neighbors that is the closest to destination. The algorithm fails if i>S does not have any neighbor that is closer to destination than i>S. i>FACE algorithm guarantees the delivery of i>m if the network, modeled by unit graph, is connected. i>GFG algorithm combines greedy and i>FACE algorithms. Greedy algorithm is applied as long as possible, until delivery or a failure. In case of failure, the algorithm switches to i>FACE algorithm until a node closer to destination than last failure node is found, at which point greedy algorithm is applied again. Past traffic does not need to be memorized at nodes. In this paper we further improve the performance of i>GFG algorithm, by reducing its average hop count. First we improve the i>FACE algorithm by adding a sooner-back procedure for earlier escape from i>FACE mode. Then we perform a i>shortcut procedure at each forwarding node i>S. Node i>S uses the local information available to calculate as many hops as possible and forwards the packet to the last known hop directly instead of forwarding it to the next hop. The second improvement is based on the concept of dominating sets. Each node in the network is classified as internal or not, based on geographic position of its neighboring nodes. The network of internal nodes defines a connected dominating set, i.e., and each node must be either internal or directly connected to an internal node. In addition, internal nodes are connected. We apply several existing definitions of internal nodes, namely the concepts of intermediate, inter-gateway and gateway nodes. We propose to run i>GFG routing, enhanced by shortcut procedure, on the dominating set, except possibly the first and last hops. The performance of proposed algorithms is measured by comparing its average hop count with hop count of the basic i>GFG algorithm and the benchmark shortest path algorithm, and very significant improvements were obtained for low degree graphs. More precisely, we obtained localized routing algorithm that guarantees delivery and has very low excess in terms of hop count compared to the shortest path algorithm. The experimental data show that the length of additional path (in excess of shortest path length) can be reduced to about half of that of existing i>GFG algorithm.

オルトエステル糖の合成，構造，およびその応用

Spiro orthoesters between sugar molecules have been found in the orthosomycin family of antibiotics. This article summarizes our recent works on orthoester sugars, which focus on preparation, structure determination, and reactivities to anions. A series of orthoesters were prepared from monosccharides with TMSOMe and TMSOTf. The configurations of the spiro carbons of these orthoesters were determined or estimated by X-ray crystallographic analysis and molecular modeling studies, which revealed the significance of anomeric effect for these molecules. The reductive cleavage of orthoester sugars afforded the corresponding glycosides with exclusive β-selectivity even in the cases of mannosides. Treatment of AlMe3 as a methyl anion source to orthoesters caused sequencial ring opening to afford enol ethers, by which a novel shortcut procedure for cyclitol synthesis was developed. Spiro keto-disaccharides, structurally related to orthoester sugars, were also prepared, and their structures were determined or estimated by X-ray crystallographic analysis and NMR studies.

Simulation of a Multicomponent Batch Distillation Column with Total Reflux through the Distillate Receiver

A shortcut procedure applicable to a multicomponent distillation in a batch column with a distillate receiver under total reflux condition was developed. It is based on the assumptions of constant molar overflow, constant vapor boilup rate, and constant relative volatilities. The effect of liquid holdup in each stage and condenser is taken into consideration in modeling the dynamic behavior of the batch column. Estimates of the volume of the distillate receiver, changes in compositions in the receiver and still, concentration profiles of the column, and total distillation time required to complete the separation can be made in the proposed model. Illustrative calculations were performed for the separation of a quaternary system for two cases: an initially empty distillate receiver and an initially filled-up distillate receiver.

Low cost, short-cut procedure for fabricating metal copings

Low cost, short-cut procedure for fabricating metal copings

Minimum Reflux for Batch Distillations of Ideal and Nonideal Mixtures at Constant Reflux

This paper presents a short-cut procedure for estimating the instantaneous separation performance in batch columns having an infinite number of stages that it is applicable to nonideal mixtures with any number of components. The model allows the estimation of the instantaneous top composition without resorting to stage-by-stage computation and therefore can be used both as a method for rapid simulation of the batch operation and as a procedure for calculating the minimum-energy demand. A key aspect of the method is the determination of the different regimes that can be found during the operation of batch columns. Each one of the different regimes is controlled by a pinch that determines the geometry of the internal profiles. For systems with constant relative volatilities, the presented approach is compared with the use of the Underwood equation to determine the instantaneous separation column performance. We show that both methods are equivalent. This analysis also gives an interpretation of the application of the Underwood equation in the context of batch rectification. Finally, we analyze the application of the model to highly nonideal mixtures with azeotropes and distillation boundaries and briefly discuss the modifications that have to be introduced to extend the method.