Scaling-up Technique Research Articles

A temporary immersion system for mass micropropagation of pitahaya (Hylocereus undatus)

Scaling-up techniques in temporary immersion systems are an alternative for commercial micropropagation. In vitro propagation of pitahaya (Hylocereus undatus) using temporary immersion with liquid culture medium improves micropropagation efficiency compared to the conventional method in semisolid medium. The objective of this work was to evaluate the efficiency of traditional culture and temporary immersion during micropropagation of pitahaya to facilitate the rapid establishment of new commercial plantations of high genetic and phytosanitary quality. Semisolid culture, liquid media in partial immersion and temporary immersion in an Ebb-and-Flow bioreactor were evaluated. Also, in temporary immersion, different immersion frequencies (every 4, 8, 12, and 16h) and culture densities (5, 10, 15 and 20 explants per bioreactor) were evaluated. For the multiplication stage, new shoots and length were recorded per explant at 45 d of in vitro culture and in the acclimatization stage, the survival percentage was determined at 30 d of greenhouse cultivation. A temporary immersion of 2min every 4h and 15 explants per bioreactor was the best culture system, obtaining on average 10.7 shoots per explant with a length of 1.9cm. No significant differences were observed among treatments during acclimatization, obtaining survival percentages of 98%-100%. This study reports for the first time a protocol for scaling-up techniques in temporary immersion for commercial micropropagation of pitahaya (and for any species of the Cactaceae family) and its establishment in a productive plantation.

Balgran: solving issues of an NGO in Jammu and Kashmir

Learning outcomes The learning outcomes have been prepared in accordance with Bloom’s Taxonomy (Bloom et al., 1956). After completing the case, the students shall be able to do the following: • describe the challenges faced by the not-for-profit, non-governmental and voluntary organizations operating at a local level in a conflict-ridden zone (knowledge). • Explain the key features, roles and typologies associated with non-governmental organizations (NGOs) (comprehension), apply such typologies to specific organizations (application) and differentiate between social enterprises and NGOs (analysis). • Analyse various scaling-up techniques and infer the technique(s) used or can be potentially used by a particular organization (analysis). • Synthesize different elements of the organizational environment and reflect on the potential influence of these elements on an organization (synthesis). • Develop frameworks by applying institutional theory and motivations for volunteerism to map challenges of organizational legitimacy and volunteer turnover, respectively, as well as make recommendations to tackle these challenges (synthesis and evaluation) • Develop recommendations for the problems faced by not-for-profit voluntary NGOs (evaluation). Case overview/synopsis Balgran, a local not-for-profit non-governmental voluntary organization operating in the conflict-ridden state of Jammu and Kashmir (J&K), India was established in the year 1975 to empower destitute, orphans, abandoned and socially handicapped children. Since its inception, Balgran has expanded its services at a rapid pace including Bal Bharti public school, health care centre, vocational training and a computer centre. Mr A.K. Khajuria, President of Balgran, was concerned about the high turnover of the voluntary staff, mistrust among the potential donors concerning fund management of NGOs and inadequate funding. Mr Khajuria after a few failed attempts at resolving these issues, called for a meeting of the members of the governing body in February 2019 to decide the future plan of action to resolve these issues. Through this case, the students can understand the challenges faced by local NGOs in general and unique challenges (mistrust among potential donors) faced by NGOs operating in conflict-ridden areas such as J&K. The students will be able to enhance their skills in brainstorming and making recommendations while framing possible solutions to the challenges faced by Balgran. The case seeks to enable the students to comprehend the features and typologies associated with NGOs; the role played by local NGOs in community development; differences between social enterprises and NGOs; scaling-up techniques and paths with special reference to local NGOs and the environmental factors that can potentially influence the operation of NGOs. Complexity academic level This case is suitable for undergraduate and graduate-level students learning social entrepreneurship, social work and management of alternate organizations such as NGOs. This case could be used to discuss concepts related to not-for-profit organizations operating in voluntary settings. Supplementary materials Teaching Notes are available for educators only. Subject code CSS 3: Entrepreneurship.

Advancements on scaling-up simulation of Proton Exchange Membrane Fuel Cells impedance through Buckingham Pi theorem

This article addresses a generalized scaling-up technique applied to proton exchange membrane fuel cells. Such a methodology allows simulating the impedance related to a full stack from that of a single cell or short stack, combining experimental data with physical reasoning and phenomenological modelling. The use of such technique can reduce electrochemical impedance spectroscopy testing costs, with a significant impact on fuel cell manufacturing and performance assessment processes. The procedure described in this paper relies on a former approach, already presented by the authors, which has been improved with respect to two main aspects. Firstly, non-dimensional parameters are computed, by referring to the Buckingham Pi theorem, through a generalized physical model. Secondly, single cell or short stack internal states (i.e., water content and limiting current) are evaluated through significant information gained from impedance measurements and inverse modelling. Stack impedance simulation is performed through proper internal states distribution assumptions. To prove the consistency and robustness of the proposed technique, experimental data taken from the literature and the European funded project HEALTH-CODE are used, with stack impedance accurately reproduced by means of only a single cell spectrum.

Cooperative effect of polyvinylpyrrolidone and HPMC E5 on dissolution and bioavailability of nimodipine solid dispersions and tablets

Solid dispersion (SD) systems have been extensively used to increase the dissolution and bioavailability of poorly water-soluble drugs. To circumvent the limitations of polyvinylpyrrolidone (PVP) dispersions, HPMC E5 was applied in the formulation process and scaling-up techniques, simultaneously. In this study, SD of nimodipine (NMP) and corresponding tablets were prepared through solvent method and fluid bed granulating one step technique, respectively. Discriminatory dissolution media were used to obtain reliable dissolution results. Meanwhile, the stability study of SDs was investigated with storage under high temperature and humidity conditions. Moreover, the solubility of SDs was measured to explore the effect of carriers. The preparations were characterized by DSC, PXRD, and FTIR. Dramatical improvements in the dissolution rate of NMP were achieved by the ingenious combination of the two polymers. Binary NMP/PVP/HPMC-SDs released steadily, while the dissolution of single NMP/PVP-SDs decreased rapidly in water. The fluid-bed tablets (FB-T) possessed a similar dissolution behavior to the commercial Nimotop™ tablets. The characterization patterns implied that NMP existed in an amorphous state in our SDs. Furthermore, the results of stability tests suggested a better stability of the binary SDs. A special cooperative effect of PVP and HPMC was discovered on dissolution characteristics of NMP SDs and tablets, which could be extended to other drugs henceforth. Finally, the bioavailability of FB-T was evaluated in beagle dogs with Nimotop™ as the reference, and the results showed a higher AUC0–12hvalue for FB-T.

Scaling-Up Techniques for the Nanofabrication of Cell Culture Substrates via Two-Photon Polymerization for Industrial-Scale Expansion of Stem Cells.

Stem-cell-based therapies require a high number (106–109) of cells, therefore in vitro expansion is needed because of the initially low amount of stem cells obtainable from human tissues. Standard protocols for stem cell expansion are currently based on chemically-defined culture media and animal-derived feeder-cell layers, which expose cells to additives and to xenogeneic compounds, resulting in potential issues when used in clinics. The two-photon laser polymerization technique enables three-dimensional micro-structures to be fabricated, which we named synthetic nichoids. Here we review our activity on the technological improvements in manufacturing biomimetic synthetic nichoids and, in particular on the optimization of the laser-material interaction to increase the patterned area and the percentage of cell culture surface covered by such synthetic nichoids, from a low initial value of 10% up to 88% with an optimized micromachining time. These results establish two-photon laser polymerization as a promising tool to fabricate substrates for stem cell expansion, without any chemical supplement and in feeder-free conditions for potential therapeutic uses.

Fault-Tolerant Scheduling for Real-Time Scientific Workflows with Elastic Resource Provisioning in Virtualized Clouds

Clouds are becoming an important platform for scientific workflow applications. However, with many nodes being deployed in clouds, managing reliability of resources becomes a critical issue, especially for the real-time scientific workflow execution where deadlines should be satisfied. Therefore, fault tolerance in clouds is extremely essential. The PB (primary backup) based scheduling is a popular technique for fault tolerance and has effectively been used in the cluster and grid computing. However, applying this technique for real-time workflows in a virtualized cloud is much more complicated and has rarely been studied. In this paper, we address this problem. We first establish a real-time workflow fault-tolerant model that extends the traditional PB model by incorporating the cloud characteristics. Based on this model, we develop approaches for task allocation and message transmission to ensure faults can be tolerated during the workflow execution. Finally, we propose a dynamic fault-tolerant scheduling algorithm, FASTER, for realtime workflows in the virtualized cloud. FASTER has three key features: 1) it employs a backward shifting method to make full use of the idle resources and incorporates task overlapping and VM migration for high resource utilization, 2) it applies the vertical/horizontal scaling-up technique to quickly provision resources for a burst of workflows, and 3) it uses the vertical scaling-down scheme to avoid unnecessary and ineffective resource changes due to fluctuated workflow requests. We evaluate our FASTER algorithm with synthetic workflows and workflows collected from the real scientific and business applications and compare it with six baseline algorithms. The experimental results demonstrate that FASTER can effectively improve the resource utilization and schedulability even in the presence of node failures in virtualized clouds.

Budget Allocation for Maximizing Viral Advertising in Social Networks

Viral advertising in social networks has arisen as one of the most promising ways to increase brand awareness and product sales. By distributing a limited budget, we can incentivize a set of users as initial adopters so that the advertising can start from the initial adopters and spread via social links to become viral. Despite extensive researches in how to target the most influential users, a key issue is often neglected: how to incentivize the initial adopters. In the problem of influence maximization, the assumption is that each user has a fixed cost for being initial adopters, while in practice, user decisions for accepting the budget to be initial adopters are often probabilistic rather than deterministic. In this paper, we study optimal budget allocation in social networks to maximize the spread of viral advertising. In particular, a concave probability model is introduced to characterize each user’s utility for being an initial adopter. Under this model, we show that it is NP-hard to find an optimal budget allocation for maximizing the spread of viral advertising. We then present a novel discrete greedy algorithm with near optimal performance, and further propose scaling-up techniques to improve the time-efficiency of our algorithm. Extensive experiments on real-world social graphs are implemented to validate the effectiveness of our algorithm in practice. The results show that our algorithm can outperform other intuitive heuristics significantly in almost all cases.

Scaling up adsorption media reactors for copper removal with the aid of dimensionless numbers

Adsorption media may be used to sorb copper in an aquatic environment for pollution control. Effective design of adsorption media reactors is highly dependent on selection of the hydraulic residence time when scaling up a pilot-scale reactor to a field-scale reactor. This paper seeks to improve scaling-up technique of the reactor design process through the use of the Damköhler and Péclet numbers via a dimensional analysis. A new scaling-up theory is developed in this study through a joint consideration of the Damköhler and Péclet numbers for a constant media particle size such that a balance between transport control and reaction control can be harmonized. A series of column breakthrough tests at varying hydraulic residence times revealed a clear peak adsorption capacity at a Damköhler number of 2.74. The Péclet numbers for the column breakthrough tests indicated that mechanical dispersion is an important effect that requires further consideration in the scaling-up process. However, perfect similitude of the Damköhler number cannot be maintained for a constant media particle size, and relaxation of hydrodynamic similitude through variation of the Péclet number must occur.

Crosswell Technologies: New Solutions for Enhanced Reservoir Surveillance

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 144271, ’Crosswell Technologies: New Solutions for Enhanced Reservoir Surveillance,’ by Bruce Marion, SPE, Muhammad Safdar, SPE, Michael Wilt, SPE, Ping Zhang, Fabian Loh, SPE, and Ajay Nalonnil, SPE, Schlumberger, prepared for the SPE Enhanced Oil Recovery Conference, Kuala Lumpur, 19-21 July 2011. The paper has not been peer reviewed. Resolution and measurement diversity help characterize the subsurface and help optimize reservoir management. Crosswell measurements image the interwell space at reservoir scale. Crosswell-seismic data provide high-resolution reflection images of reservoir architecture. Crosswell electromagnetics (EM) expands the scale investigated by traditional resistivity logging to deliver a more extensive understanding of fluid distribution and movement at reservoir scale, away from the wells. These techniques complement each other, but integrating the measured data with conventional logs and surface data into the modeling workflow gives new insight into reservoir structure and fluid movement in the formation. Introduction Crosswell measurements enable greater understanding of reservoir heterogeneity and improve fluid-front monitoring. Geologic heterogeneity and the complexity of reservoir behavior when subjected to improved-recovery processes make crosswell surveillance useful in constraining scaling-up techniques during static modeling and in providing better predictability of injection performance. The two case studies detailed in the full-length paper describe early applications of crosswell surveys in the USA in the Chevron-operated Cymric field in California’s San Joaquin Valley. Theory Crosswell seismic produces images of the interwell space with a vertical resolution five to 10 times higher than that of surface-seismic data. Both direct- and reflected-wave fields are processed to provide a detailed image of the reservoir. By use of higher-frequency sources deployed alongside the reservoir interval, crosswell-seismic surveying generates high-vertical-resolution reflection images with resolution on the order of 1 to 3 m. This is the result of high bandwidth of the transmitters used during acquisition, with upper frequencies ranging from 800 Hz to 2 kHz. Because seismic velocity is sensitive to pressure, temperature, and saturation changes caused by the injection of CO2, gas, and steam, crosswell seismic provides valuable information for reservoir characterization and for monitoring injection performance and efficiency. Crosswell seismic can detect compressional-wave velocity changes as small as 1 to 3% reliably. Also, because the migrated-reflection section provides a high-resolution image of the structure between wells, it helps determine the geologic causes of the observed performance and fluid flow. Crosswell EM is a natural extension of the single-well induction-logging method whereby the transmitter and receiver are placed in separate wells. This geometry provides high-resolution resistivity distribution of the subsurface between the wells. When obtained at different timesteps during injection and production, this resistivity distribution provides valuable information that can be integrated with other data to interpret changes in the reservoir rock and the fluid distribution between wells. These data are valuable in updating the reservoir model with reduced uncertainty and enhanced predictability. Resistivity is especially responsive to changes in fluid composition in the reservoir and is an excellent indicator of temperature-related changes in the reservoir.

A Unified Scaling-Up Technique for Pneumatic Conveying Systems

A major challenge facing the designers of pneumatic transportation systems is how to scale up reliably based on the results from pilot-scale test facilities. Further, even if dense phase flow condition prevails at the start of the conveying system, it may be a dilute phase flow condition at the end of the pipeline. Hence, any scaling-up technique should be able to address the dynamic change of flow condition along the pipeline. The scaling-up technique presented here using the pressure drop prediction models based on modified Darcy-Weisbach equation successfully addresses these dynamic changes. It has been shown that the pressure drop coefficient ‘K,’ as defined by the models, is independent of the pipe diameter. Further, in the case of vertical conveying, ‘K’ has been shown to be independent of particle size distribution for a given material. The predicted pressure values were found to be in reasonably good agreement with the experimental results varying from 3.5% to 19.9%.

A Possible Scaling-up Technique for Dense Phase Pneumatic Conveying

ABSTRACT In this article experimental findings have been presented to show that the pressure drop coefficient (K) for vertical and horizontal pneumatic conveying for a given bulk material follows a certain pattern. The pressure drop coefficient for vertical pneumatic conveying for a given material has been found to be independent of any variation of particle size distribution, within experimental limits. The pressure drop prediction technique proposed by the authors previously has been validated with the test results of alumina and bentonite.

A Simple Technique for Scaling Up Pneumatic Conveying Systems

A brief survey has shown that although scaling-up techniques in pneumatic conveying systems have generally been based on laboratory-scale test data, there still exists a divergence of opinions about the right choice of certain basic parameters such as solids friction factor and air friction factor. In this article, a simple model for pressure drop calculation has been proposed based on the classical Darcy's equation with some modifications. A parameter K, called pressure drop coefficient, has been shown to be independent of pipe diameter and hence suitable for scaling up to pipe sizes different from those used in laboratory-scale tests. For each of the bulk material and pipe size combinations used in this study, we calculated the standard deviation of predicted pressure values from the experimental values along the central 45° line passing through the origin; it varied from±165 mbar to a maximum±285 mbar. It has been shown that the model can be used for both horizontal and vertical pneumatic conveying.

Advanced Honeycomb Adsorbent and Scaling-Up Technique for Thermal Swing Adsorptive VOC Concentrators.

熱安定性の高い, セラミック繊維紙をハニカム構造を持つ吸着体マトリックスに成形し, 熱処理後, ハイシリカゼオライトとバインダーを分散させたシリカゾルの液に浸した.更に乾燥工程を経て, このマトリックスの繊維間の空隙にハイシリカゼオライトを含浸固着させ, 再生時に着火の恐れの無いVOC濃縮用のハニカム型吸着剤ローターを得た.ハニカム成形時に無機接着剤セピオライト (山皮) を用いた新しい吸着剤ローターでは, セピオライトを用いない従来の吸着剤ローターに比べ1.6～3.2倍の破壊強度の増加がみられた.又, この吸着剤ローター用に二種類の異なった形状のフッ素ゴムシールを開発し, 各ゾーン間及び外周部への空気の漏洩速度を測定し, 漏洩量が十分低い事を確認した.この製法に基づく吸着剤ローターとシール構造を用いて3,950mmφ×450mmLの大型VOC濃縮装置を製作して実機運転した結果, 代表的なVOCに対し, 10倍濃縮で90～95%除去という小型試験と同等の高い濃縮性能を持つことが判った.

Large-scale properties for two-phase flow in random porous media

Hydrocarbon contaminants in the subsurface are important sources of pollution in aquifers. Hence, mathematical models of these flows have become key tools in environmental studies. In this paper we are interested in the flow in the saturated zone. Simulation of two-phase flow in large, complex heterogeneous domains often requires an unacceptably large number of computational grid blocks. Despite recent progress in computational methods and tools, we must call upon special techniques in order to use larger grid blocks while compensating for intracell variations in rock properties and fluid saturations. The use of pseudo-functions is one way of increasing grid dimensions to a more tractable level with a minimal loss of simulation representativeness. This change of scale problem has also been treated theoretically by different scaling-up techniques, such as large-scale averaging. This method calculates the transport equations and the effective properties at a given scale by an averaging process over the equations corresponding to a lower scale. This procedure leads to a closure problem which is very complex in the general case. Previously a first solution of the large-scale averaging problem was proposed in the quasi-static case corresponding to local capillary equilibrium. In the general case of a heterogeneous medium with a complex geometry, this boundary value problem (closure problem) can be solved by numerical methods. For this purpose, after having chosen a grid-block description of our system in accordance with the description used in reservoir simulators, we have implemented a three-dimensional (3-D) numerical resolution of the closure problem. The most important variations in the rock properties are associated with the permeability. We have therefore generated porous media with a random permeability distribution using different methods. Other multiphase properties are chosen to depend on the permeability. The properties of the closure problem in the case of randomly generated porous media are investigated. In particular, we give the conditions under which the general form of the local capillary pressure and relative permeability curves are recovered at the large scale. Particular properties related to each generation method are stated. The equivalent properties are calculated using averages over the results of many realizations of a given medium. The influence of the size of the averaging surface for a given correlation length as a function of the variance of the permeability is studied. We have therefore established some general rules for the calculation of the large-scale properties of random porous media.