Search

This paper presents an optimization framework based on an open-source CAD system and CFD solver. In this work, the high-fidelity flow solutions and surface sensitivities are obtained using the primal and discrete adjoint formulations of $SU^2$. This paper shows the direct use of CAD models for optimization by developing a CAD system application programming interface, and creating a link between CAD-MESH-CFD analysis. A methodology to obtain geometric sensitivities is introduced, enabling the calculation of accurate gradients with respect to CAD variables and the deformation of the analysis mesh during the optimization process. This methodology guarantees that the new surface mesh lies exactly on the computer-aided-design geometry. The optimization framework is applied to a rectangular wing and a three section high-lift aerofoil configuration derived from the NASA CRM-HL configuration. Both geometries are created using FreeCAD. The performance objectives are to decreased drag while constraining the lift to be above a desired value. The twist distribution of the wing was parameterized within the CAD system, allowing the minimization of the induced drag by obtaining a nearly elliptical lift distribution. For the high-lift configuration, the position and rotation of the flap and slat were parameterized with respect to the original section; the final optimised positions yield a drag reduction of approximately 16.5\%. These results show that the CAD parameterization can be reliably used to obtain efficient optimums, while operating directly on the CAD geometries.

This paper demonstrates developments that introduce generalized Bezier components in the Moving Morphable Components (MMC) optimization framework. Methods of enhancing the parameterization of the components to provide the opportunity for a better optimum, than can be achieved using existing approaches, are also described. The use of control points and Bezier curves for representing structural components provides both additional flexibility in the shape and a parameterization that complies with extrude and swept feature-based templates available in commercial computer-aided design (CAD) packages. Methods of representing these structural components, calculating analytical derivatives, and numerical examples demonstrating their integration in the MMC framework, are presented for a series of author-derived and literature problems. A successive refinement technique demonstrates how the additional flexibility in the structural components enables progressive improvement in the objective function. For the examined problems, increasing the design variables per component (from 5 to 15) resulted in solutions with 6% to 36% reduction in compliance. This improvement was achieved without increasing the number of components in the design space.

The transformation in manufacturing capability being driven by new processes, such as additive manufacturing, offers huge potential for product innovation and opportunity to create bespoke designs tailored to individual specifications or needs. However, current design systems and tools are not yet capable of fully capitalizing on these new technologies and new approaches are needed. Many current methodologies are top-down and sequential, offering limited flexibility and an overly constrained design space. Post-processing is needed to ensure that a design can be manufactured. This work presents a novel bottom-up methodology to generate designs that can be tightly integrated with the additive manufacturing environment and that can respond flexibly to changes in that environment. Focusing on overhang as an exemplar manufacturing constraint, the method engenders changes in the design either by locally adjusting the geometry to stay within limits or by adding an appropriate support structure. The method is bio-inspired, based on strategies observed in natural systems, particularly in biological growth and development. The design geometry is grown in a computer-aided design-based, bio-inspired generative design system called ‘Biohaviour’. This process is similar to plant growth, and the design’s final configuration, shape, and size are informed by both the manufacturing capability and internal design stresses. The approach is demonstrated for overhang limit and build orientation and is extensible to any general situation.

Background: \ud The SARS-CoV-2 delta (B.1.617.2) variant was first detected in England in March, 2021. It has since rapidly become the predominant lineage, owing to high transmissibility. It is suspected that the delta variant is associated with more severe disease than the previously dominant alpha (B.1.1.7) variant. We aimed to characterise the severity of the delta variant compared with the alpha variant by determining the relative risk of hospital attendance outcomes.\ud \ud Methods: \ud This cohort study was done among all patients with COVID-19 in England between March 29 and May 23, 2021, who were identified as being infected with either the alpha or delta SARS-CoV-2 variant through whole-genome sequencing. Individual-level data on these patients were linked to routine health-care datasets on vaccination, emergency care attendance, hospital admission, and mortality (data from Public Health England's Second Generation Surveillance System and COVID-19-associated deaths dataset; the National Immunisation Management System; and NHS Digital Secondary Uses Services and Emergency Care Data Set). The risk for hospital admission and emergency care attendance were compared between patients with sequencing-confirmed delta and alpha variants for the whole cohort and by vaccination status subgroups. Stratified Cox regression was used to adjust for age, sex, ethnicity, deprivation, recent international travel, area of residence, calendar week, and vaccination status.\ud \ud Findings: \ud Individual-level data on 43 338 COVID-19-positive patients (8682 with the delta variant, 34 656 with the alpha variant; median age 31 years [IQR 17–43]) were included in our analysis. 196 (2·3%) patients with the delta variant versus 764 (2·2%) patients with the alpha variant were admitted to hospital within 14 days after the specimen was taken (adjusted hazard ratio [HR] 2·26 [95% CI 1·32–3·89]). 498 (5·7%) patients with the delta variant versus 1448 (4·2%) patients with the alpha variant were admitted to hospital or attended emergency care within 14 days (adjusted HR 1·45 [1·08–1·95]). Most patients were unvaccinated (32 078 [74·0%] across both groups). The HRs for vaccinated patients with the delta variant versus the alpha variant (adjusted HR for hospital admission 1·94 [95% CI 0·47–8·05] and for hospital admission or emergency care attendance 1·58 [0·69–3·61]) were similar to the HRs for unvaccinated patients (2·32 [1·29–4·16] and 1·43 [1·04–1·97]; p=0·82 for both) but the precision for the vaccinated subgroup was low.\ud \ud Interpretation: \ud This large national study found a higher hospital admission or emergency care attendance risk for patients with COVID-19 infected with the delta variant compared with the alpha variant. Results suggest that outbreaks of the delta variant in unvaccinated populations might lead to a greater burden on health-care services than the alpha variant.\ud \ud Funding: \ud Medical Research Council; UK Research and Innovation; Department of Health and Social Care; and National Institute for Health Research.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections were rising during early summer 2021 in many countries as a result of the Delta variant. We assessed reverse transcription polymerase chain reaction swab positivity in the Real-time Assessment of Community Transmission–1 (REACT-1) study in England. During June and July 2021, we observed sustained exponential growth with an average doubling time of 25 days, driven by complete replacement of the Alpha variant by Delta and by high prevalence at younger, less-vaccinated ages. Prevalence among unvaccinated people [1.21% (95% credible interval 1.03%, 1.41%)] was three times that among double-vaccinated people [0.40% (95% credible interval 0.34%, 0.48%)]. However, after adjusting for age and other variables, vaccine effectiveness for double-vaccinated people was estimated at between ~50% and ~60% during this period in England. Increased social mixing in the presence of Delta had the potential to generate sustained growth in infections, even at high levels of vaccination.

Collaborative governance applied to environmental issues is becoming more common, and evaluation of such efforts can provide useful information for multiple audiences. However, due to a variety of challenges, collaborative governance practitioners rarely evaluate the outcomes of collaboration and their contributions to these efforts. With these challenges in mind, the William D. Ruckelshaus Center designed an evaluation framework that can meet multiple parties’ objectives, be integrated into practitioners’ existing services, and balance flexibility and practicality with rigor and replicability. The Center conducted a pilot of this framework on a collaborative watershed management effort in southeastern Washington State, where the Center had previously assisted with organizational development. The resulting evaluation highlights a variety of social, knowledge-based, and economic outcomes for the collaborative, as well as lessons for practitioners and evaluators of collaborative governance. We suggest that this methodology can be useful for practitioners interested in evaluating similar collaborative efforts.

This paper describes an implementation of a method capable of integrating parametric, feature based, CAD models based on commercial software (CATIA) with the SU2 software framework. To exploit the adjoint based methods for aerodynamic optimisation within the SU2, a formulation to obtain geometric sensitivities directly from the commercial CAD parameterisation is introduced, enabling the calculation of gradients with respect to CAD based design variables. To assess the accuracy and efficiency of the alternative approach, two aerodynamic optimisation problems are investigated: an inviscid, 3D, problem with multiple constraints, and a 2D high-lift aerofoil, viscous problem without any constraints. Initial results show the new parameterisation obtaining reliable optimums, with similar levels of performance of the software native parameterisations. In the final paper, details of computing CAD sensitivities will be provided, including accuracy as well as linking geometric sensitivities to aerodynamic objective functions and constraints; the impact in the robustness of the overall method will be assessed and alternative parameterisations will be included.

Adjoint methods have proven to be an efficient way of calculating the gradient of an objective function with respect to a shape parameter for optimisation, with a computational cost nearly independent of the number of the design variables [1]. The approach in this paper links the adjoint surface sensitivities (gradient of objective function with respect to the surface movement) with the parametric design velocities (movement of the surface due to a CAD parameter perturbation) in order to compute the gradient of the objective function with respect to CAD variables. For a successful implementation of shape optimization strategies in practical industrial cases, the choice of design variables or parameterisation scheme used for the model to be optimized plays a vital role. Where the goal is to base the optimization on a CAD model the choices are to use a NURBS geometry generated from CAD modelling software, where the position of the NURBS control points are the optimisation variables [2] or to use the feature based CAD model with all of the construction history to preserve the design intent [3]. The main advantage of using the feature based model is that the optimized model produced can be directly used for the downstream applications including manufacturing and process planning.This paper presents an approach for optimization based on the feature based CAD model, which uses CAD parameters defining the features in the model geometry as the design variables. In order to capture the CAD surface movement with respect to the change in design variable, the “Parametric Design Velocity” is calculated, which is defined as the movement of the CAD model boundary in the normal direction due to a change in the parameter value.The approach presented here for calculating the design velocities represents an advancement in terms of capability and robustness of that described by Robinson et al. [3]. The process can be easily integrated to most industrial optimisation workflows and is immune to the topology and labelling issues highlighted by other CAD based optimisation processes. It considers every continuous (“real value”) parameter type as an optimisation variable, and it can be adapted to work with any CAD modelling software, as long as it has an API which provides access to the values of the parameters which control the model shape and allows the model geometry to be exported. To calculate the movement of the boundary the methodology employs finite differences on the shape of the 3D CAD models before and after the parameter perturbation. The implementation procedure includes calculating the geometrical movement along a normal direction between two discrete representations of the original and perturbed geometry respectively. Parametric design velocities can then be directly linked with adjoint surface sensitivities to extract the gradients to use in a gradient-based optimization algorithm.The optimisation of a flow optimisation problem is presented, in which the power dissipation of the flow in an automotive air duct is to be reduced by changing the parameters of the CAD geometry created in CATIA V5. The flow sensitivities are computed with the continuous adjoint method for a laminar and turbulent flow [4] and are combined with the parametric design velocities to compute the cost function gradients. A line-search algorithm is then used to update the design variables and proceed further with optimisation process.

The aim of this work is to investigate an efficient CAD based adjoint process chain for calculating sensitivities of the objective function to the CAD parameter in time scales acceptable for industrial design processes.

Background and Aims: The resurgence of malaria, particularly in the developing world, is considerable and exacerbated by the development of single-gene multi-drug resistances to chemicals such as chloroquinone. Drug therapies, as recommended by the World Health Organization, now include the use of antimalarial compounds derived from Artemisia annua – in particular, the use of artemisinin-based ingredients. Despite our limited knowledge of its mode of action or biosynthesis there is a need to secure a supply and enhance yields of artemisinin. The present study aims to determine how plant biomass can be enhanced while maximizing artemisinin concentration by understanding the plant's nutritional requirements for nitrogen and potassium. Methods: Experiments were carried out, the first with differing concentrations of nitrogen, at 6, 31, 56, 106, 206 or 306 mg L–1 being applied, while the other differing in potassium concentration (51, 153 or 301 mg L–1). Nutrients were supplied in irrigation water to plants in pots and after a growth period biomass production and leaf artemisinin concentration were measured. These data were used to determine optimal nutrient requirements for artemisinin yield. Key Results: Nitrogen nutrition enhanced plant nitrogen concentration and biomass production successively up to 106 mg N L–1 for biomass and 206 mg N L–1 for leaf nitrogen; further increases in nitrogen had no influence. Artemisinin concentration in dried leaf material, measured by HPLC mass spectroscopy, was maximal at a nitrogen application of 106 mg L–1, but declined at higher concentrations. Increasing potassium application from 51 to 153 mg L–1 increased total plant biomass, but not at higher applications. Potassium application enhanced leaf potassium concentration, but there was no effect on leaf artemisinin concentration or leaf artemisinin yield. Conclusions: Artemisinin concentration declined beyond an optimal point with increasing plant nitrogen concentration. Maximization of artemisinin yield (amount per plant) requires optimization of plant biomass via control of nitrogen nutrition.

The antimalarial drug artemisinin (ART) is commercially extracted from the medicinal plantArtemisia annuaL. Here, we report the screening of 70A. annuaplants representing 14 diverse germplasm accessions sourced from around the world, and identify lines containing >2% ART. These extremely high-yielding individuals have been maintained as vegetative clones, and they represent promising germplasm resources for futureA. annuabreeding programmes.

Tropine (tropan-3α-ol) is an intermediate in the formation of hyoscyamine. An acyltransferase activity that can acetylate tropine using acetyl-coenzyme A as cosubstrate has been found in transformed root cultures of Datura stramonium . A further acyltransferase activity that acetylates pseudotropine (tropan-3β-ol) with acetyl-coenzyme A is also present. These two activities can be partially resolved by anion-exchange chromatography, some fractions containing only the pseudotropine-utilizing activity. The basic properties of these two enzymes are reported and their roles in forming the observed alkaloid spectrum of D. stramonium roots discussed.

A highly integrated transmitter IC fabricated in Conexant's 0.35 um SiGe BiCMOS process and packaged in a 6 mm /spl times/ 6 mm Land Grid Array (LGA) package provides dual band/tri-mode transmitter functionality in a CDMA handset meeting TIA/EIA 98-D specifications. This chip upconverts the I/Q baseband signals to RF in two stages and delivers the amplified RF signal to the power amplifier. It consists of the following stages: an I/Q modulator, VHF VCO, VHF PLL, IF VGA, UHF LO buffer, UHF PLL, 3 wire serial interface, RF image reject upconverter, a cellular PA driver and dual PCS drivers. It is designed to deliver 8 dBm in CDMA mode in Cellular band, 11 dBm in AMPS mode and 9 dBm in CDMA mode in PCS band at 90 mA, 88 mA and 108 mA respectively at nominal supply and temperature. It also provides IF dynamic range of 80 dB in the IF VGA and RF Gain dynamic range of 20 dB in Cellular band and 15 dB in PCS band. The IC operates from a supply ranging from 2.7 V to 3.3 V and a temperature range of -30C to 85C.

This paper presents a single chip, superhetrodyne receiver IC capable of supporting dual-band, tri-mode handsets. Supported standards include W-CDMA, CDMA (IS-98-C) and AMPS. The receiver consists of multistep gain LNAs, high performance RF mixers with adjustable linearity, a variable gain amplifier, on chip VCO cores, and an IQ downconverter. The IC is fabricated in a 35 GHz f/sub t/ Si BiCMOS process and packaged into a 48 pin 7 mm/spl times/7 mm land grid array (RF-LGA/sup TM/) chipscale package.

In this paper, a two device chip-set integrating the RF transceiver front-end function for the dual-band, dual-mode CDMA/AMPS cellular telephone standard TIA/EIA-98 is described. Fabricated in a double polysilicon, 25 GHz f/sub T/, silicon bipolar process, the transceiver achieves a total power dissipation of less than 480 mW at 3 V with 9 dBm transmitter power.

A report in an Ecuadorian anthropological monograph that Petunia violacea was used as a hallucinogen by some native South American people under the name Shanin. (Alvear, 1971) stimulated interest in the ethnobotanical literature (Schultes, 1975). This was particularly interesting because the species is a member of the alkaloid-rich Solanaceae family. No reports of its containing alkaloids have been published to date (Raffauf, 1970). We have unsuccessfully attempted to isolate an alkaloid from this plant grown in the greenhouse, and recently interviewed the author of the original report. This communication will summarize the results of the laboratory work and the interview.

After comparing several methods of protein determination it was concluded that when polyphenolic compounds are present the most reliable method for protein is the Bradford procedure using Coomassie Brilliant Blue G-250.

The Δ 5 - β -3-OH sterols, cholesterol, ergosterol, sitosterol, and stigmasterol, reversed the antifungal activity of pimaricin on S. cerevisae while mevalonic acid, squalene and lanosterol were inactive in this respect. Several explanations for this effect were discussed.

The 2-, 4-, and 6-pyridones related to 1-methylnicotinonitrile have been synthesized and their properties compared. The 4-pyridone is a new compound and the 2-pyridone has not been obtained synthetically before. The 4- and 6-pyridones are identical to two of the products obtained from enzymatic oxidation of nicotinonitrile methiodide.

The crude extract of pyridinium oxidizing enzymes from Ricinus communis seedlings was resolved into three enzyme entities by DEAE column chromatography. Their optimal pH, temperature stability, activation energies and substrate specificities are similar. Analysis of their enzymatic products have shown that each of these enzymes catalyses the oxidation of 1-methyl-nicotinonitrile perchlorate to form 4- and 6-pyridones.

Pyridinium oxidase B from Ricinus communis, initially separated by DEAE cellulose column chromatography, was further purified. The fraction with the highest activity from Ecteola cellulose column still showed a trace of impurities in polyacrylamide gel electrophoresis. Molecular weight estimation by sucrose gradient ultracentrifugation showed that pyridinium oxidase B has an apparent molecular weight of approximately 250,000. The rate of 4- and 6-pyridone formation in the catalytic process was studied. The ratio of the 6-pyridone to 4-pyridone ranged from 3·5 to 4·1. The Km for 1-methyl-nicotinonitrile perchlorate was found to be 5 × 10−4 M for pyridinium oxidase B, and it decreased with increasing pH. An approximate pKa of 9:9 was obtained for the ionizing group involved in the enzymatic reaction. The Km values for its substrate analogues, except 1-methyl-3-acetyl pyridinium, were found to be the same. However, the value of Vm increased as the dipole moment of the 3 substituent increased. The present evidence indicates that the positively charged quaternary nitrogen is necessary for the enzyme-substrate binding, and a strong electron withdrawing group will enhance the oxidation reaction. The enzyme resembles aldehyde and xanthine oxidase in its ability to oxidize a wide variety of nitrogenous compounds.

A crude enzyme system prepared from young castorbean seedlings catalyzes the oxidation of 1-methylnicotinonitrile to the corresponding 4- and 6-pyridones. The implications of this reaction for the biosynthesis of the alkaloid ricinine are considered. Other pyridone alkaloids might be formed by similar reactions.

When dilute aqueous solutions of liver alcohol dehydrogenase were exposed to X-irradiation, there was much more inactivation in the presence of bicarbonate buffer than in phosphate buffer or in distilled water. The effect was not due to the action of any stable intermediates produced by irradiation of bicarbonate buffer, nor does it seem likely that enzyme is converted by irradiation to some long-lived metastable state whose destruction is precipitated by the presence of bicarbonate. Enzyme and bicarbonate must be present simultaneously for the effect to be observed. Several other enzymes have been investigated in this regard, and possible mechanisms discussed.

At least seven species ( Chrozophora plicata, Jatropha gossypifolia, Ricinus communis, Tragia involucrata, Trewia nudiflora, Acalypha hispida, Synadenium grantii ) in the family Euphorbiaceae have shown enzymatic oxidizing activity on salts of 1-methyl-nicotinotrile. 4- and 6-pyridones were shown to be the enzymic products in vitro for both Trewia nudiflora and Ricinus communis .

The responses of common purslane (Portulaca oleracea L.) plants to 2-methoxy-3,6-dichlorobenzoic acid (dicamba) were found to be similar in many respects to ethylene fumigation effects. Dicamba and ethylene increased the permeability of cell membranes in purslane tissues. An increased efflux of electrolytes was observed in the bending region of the stems of dicamba-treated plants. Epinastic leaves after dicamba (10 micrograms) and ethylene (microliter per liter) treatments showed an increased efflux of rubidium. The permeability effects were observable within 1 day after dicamba or ethylene application. Protein metabolism in purslane leaves was not influenced by dicamba until 2 days after treatment, as indicated by reduced nitrate reductase activity. Inhibition of phenylalanine-U-14C incorporation into protein was observed 3 days after treatment. Ethylene reduced both phenylalanine-U-14C incorporation into protein and nitrate reductase activity within 1 day. Dicamba caused a rapid increase in ethylene production in purslane plants to levels many times greater than those observed in untreated plants. It was concluded that the dicamba-enhanced production of ethylene is responsible for many of the observed effects of the herbicide.

Extracts of Papaver somniferum that had peroxidase activity were ineffective in catalysing oxidation of reticuline. Two peroxidases were purified from young seedlings and their properties examined. Only one of them was active toward indole-3-acetic acid (IAA).

Isotopic tracer experiments confirmed that glycerol and succinic acid are good precursors of the pyridine ring of ricinine in castor bean plants. Tritium from C-2 was lost from tritiated glycerol while tritium from C-1 was retained. Thus a derivative of dihydroxyacetone is likely to be intermediate. By simultaneous feeding of glycerol-1-(3)-[3H] and succinic acid-2(3)-[14C], it was hoped to find precursors of ricinine containing both labels, but none could be found. There was no evidence for the appearance of labeled quinolinic acid, which is presumed to be a precursor of ricinine.

In contrast to a previous report no free arginine, agmatine, or other low-molecular-weight guanido compound could be detected in seeds of Ricinus communis (Euphorbiaceae). A heat-stable, arginine-containing protein was isolated and identified with a previously known allergen.

There are only a few simple pyrrolidine alkaloids found in nature, although pyrrolidine (or pyrrole) rings combined into larger structures are relatively common (e.g., in the indole alkaloids). Methylated derivatives of proline or hydroxyproline could be called alkaloids but are here placed with protoalkaloids in Chapter 2; β-methylpyrroline is considered with the terpenoid alkaloids in Chapter 13.