Traditionally, standard Lagrangian-type finite elements, such as linear quads and triangles, have been the elements of choice
in the field of topology optimization. However, finite element meshes with these conventional elements exhibit the well-known
“checkerboard” pathology in the iterative solution of topology optimization problems. A feasible alternative to eliminate
such long-standing problem consists of using hexagonal (honeycomb) elements with Wachspress-type shape functions. The features
of the hexagonal mesh include two-node connections (i.e. two elements are either not connected or connected by two nodes),
and three edge-based symmetry lines per element. In contrast, quads can display one-node connections, which can lead to checkerboard;
and only have two edge-based symmetry lines. In addition, Wachspress rational shape functions satisfy the partition of unity
condition and lead to conforming finite element approximations. We explore the Wachspress-type hexagonal elements and present
their implementation using three approaches for topology optimization: element-based, continuous approximation of material
distribution, and minimum length-scale through projection functions. Examples are presented that demonstrate the advantages
of the proposed element in achieving checkerboard-free solutions and avoiding spurious fine-scale patterns from the design
optimization process. 相似文献
External insulin administration is an effective way for patients with diabetes mellitus to regulate their blood glucose. Multiple daily injections (MDIs), sensor-augmented pump (SAP) and artificial pancreas (AP) are widely adopted approaches in insulin therapy. With the increasing popularity of continuous glucose monitoring (CGM) sensors, a large number of data-enabled learning and control algorithms have been developed for MDI, SAP and AP. In this paper, we perform a systemic review concerning the state-of-the-art methodologies that are developed for MDI, SAP and AP with feedback from CGM data or other available data, from a systems and control perspective. The review characterizes the traditional learning and control methods developed for the MDI, SAP and AP, including run-to-run control, proportional–integral–derivative control, fuzzy logic control and model predictive control, as well as the discussions on the roles of machine learning technologies in MDI, SAP and AP. Finally, potential future directions on the algorithm architecture design, a unified control framework for MDI, SAP and AP algorithm design and practical usage of the MDI, SAP and AP are discussed. 相似文献
Context: Continuous processing is an innovative production concept well known and successfully used in other industries for many years. The modern pharmaceutical industry is facing the challenge of transition from a traditional manufacturing approach based on batch-wise production to a continuous manufacturing model.
Objective: The aim of this article is to present technological progress in manufacturing based on continuous and semi-continuous processing of the solid oral dosage forms.
Methods: Single unit processes possessing an alternative processing pathway to batch-wise technology or, with some modification, an altered approach that may run continuously, and are thus able to seamlessly switch to continuous manufacturing are briefly presented. Furthermore, the concept of semi-continuous processing is discussed. Subsequently, more sophisticated production systems created by coupling single unit processes and comprising all the steps of production, from powder to final dosage form, were reviewed. Finally, attempts of end-to-end production approach, meaning the linking of continuous synthesis of API from intermediates with the production of final dosage form, are described.
Results: There are a growing number of scientific articles showing an increasing interest in changing the approach to the production of pharmaceuticals in recent years. Numerous scientific publications are a source of information on the progress of knowledge and achievements of continuous processing. These works often deal with issues of how to modify or replace the unit processes in order to enable seamlessly switching them into continuous processing. A growing number of research papers concentrate on integrated continuous manufacturing lines in which the production concept of “from powder to tablet” is realized. Four main domains are under investigation: influence of process parameters on intermediates or final dosage forms properties, implementation of process analytical tools, control-managing system responsible for keeping continuous materials flow through the whole manufacturing process and the development of new computational methods to assess or simulate these new manufacturing techniques. The attempt to connect the primary and secondary production steps proves that development of continuously operating lines is possible.
Conclusion: A mind-set change is needed to be able to face, and fully assess, the advantages and disadvantages of switching from batch to continuous mode production. 相似文献
Mountain pine beetle (Dendroctonus ponderosae Hopkins) is the most destructive insect infesting mature pine forests in North America and has devastated millions of hectares of forest in western Canada. Past studies have demonstrated the use of multispectral imagery for remote identification and mapping of visible or red attack damage in forests. This study aims to detect pre-visual or green attack damage in lodgepole pine needles by means of hyperspectral measurements, particularly via continuous wavelet analysis. Field measurements of lodgepole pine stands were conducted at two sites located northwest of Edmonton, Alberta, Canada. In June and August of 2007, reflectance spectra (350-2500 nm) were collected for 16 pairs of trees. Each of the 16 tree pairs included one control tree (healthy), and one stressed tree (girdled to simulate the effects of beetle infestation). In addition, during the period of June through October 2008, spectra were collected from 15 pairs of control- and beetle-infested trees. Spectra derived from these 31 tree pairs were subjected to a continuous wavelet transform, generating a scalogram that compiles the wavelet power as a function of wavelength location and scale of decomposition. Linear relationships were then explored between the wavelet scalograms and chemical properties or class labels (control and non-control) of the sample populations in order to isolate the most useful distinguishing spectral features that related to infested or girdled trees vs. control trees.A deficit in water content is observed in infested trees while an additional deficit in chlorophyll content is seen for girdled trees. The measurable water deficit of infested and girdled tree samples was detectable from the wavelet analysis of the reflectance spectra providing a novel method for the detection of green attack. The spectral features distinguishing control and infested trees are predominantly located between 950 and 1390 nm from scales 1 to 8. Of those, five features between 1318 to 1322 nm at scale 7 are consistently found in the July and August 2008 datasets. These features are located at longer wavelengths than those investigated in previous studies (below 1100 nm) and provide new insights into the potential remote detection of green attack. Spectral features that distinguish control and girdled trees were mostly observed between 1550 and 2370 nm from scales 1 to 5. The differing response of girdled and infested trees appears to indicate that the girdling process does not provide a perfect simulation of the effects caused by beetle infestation.It remains to be determined if the location of the 1318-1322 nm features, near the edge of a strong atmospheric water absorption band, will be sufficiently separable for use in airborne detection of green attack. A plot comparing needle water content and wavelet power at 1320 nm reveals considerable overlap between data derived from both infested and control samples, though the groups are statistically separable. This obstacle may preclude a high accuracy separation of healthy and infected single individuals, but establishing threshold identification levels may provide an economical, efficient and expeditious method for discriminating between healthy and infested tree populations. 相似文献