A generalized framework for reduced‐order modeling of a wind turbine wake

A reduced‐order model for a wind turbine wake is sought from large eddy simulation data. Fluctuating velocity fields are combined in the correlation tensor to form the kernel of the proper orthogonal decomposition (POD). Proper orthogonal decomposition modes resulting from the decomposition represent the spatially coherent turbulence structures in the wind turbine wake; eigenvalues delineate the relative amount of turbulent kinetic energy associated with each mode. Back‐projecting the POD modes onto the velocity snapshots produces dynamic coefficients that express the amplitude of each mode in time. A reduced‐order model of the wind turbine wake (wakeROM) is defined through a series of polynomial parameters that quantify mode interaction and the evolution of each POD mode coefficients. The resulting system of ordinary differential equations models the wind turbine wake composed only of the large‐scale turbulent dynamics identified by the POD. Tikhonov regularization is used to recalibrate the dynamical system by adding additional constraints to the minimization seeking polynomial parameters, reducing error in the modeled mode coefficients. The wakeROM is periodically reinitialized with new initial conditions found by relating the incoming turbulent velocity to the POD mode coefficients through a series of open‐loop transfer functions. The wakeROM reproduces mode coefficients to within 25.2%, quantified through the normalized root‐mean‐square error.  A high‐level view of the modeling approach is provided as a platform to discuss promising research directions, alternate processes that could benefit stability and efficiency, and desired extensions of the wakeROM.     

Solid substrate production of Epicoccum nigrum conidia for biological control of brown rot on stone fruits

Production of conidia of Epicoccum nigrum, a biocontrol agent of the fungal pathogen Monilinia laxa, was tested in liquid- and solid-state fermentation. Liquid fermentation was conducted in 250 ml Erlenmeyer flasks containing 50 ml of a mineral medium (containing per litre: 20 g lactose, 10 g NO3K, 1 g K2HPO4, 0.5 g MgSO4.7H2O, and 1 ml of a minor-element solution), inoculated with 2 x 10(5) E. nigrum conidia ml(-1), and incubated at 20-25 degrees C and 150 rpm for 7 days. Solid-state fermentation was carried out in specially designed plastic bags (600 cm3) (VALMIC) containing either 50 g of peat/vermiculite (1:1, w/w), or 50 g of peat/vermiculite/lentil meal (1:1:1, w/w/w) with 40% (v/w) initial moisture content. Substrate was inoculated with a conidial suspension of E. nigrum to give 10(5) conidia g(-1) substrate, and bags were incubated at 20-25 degrees C for 7 days in darkness. The amount of conidia of E. nigrum obtained in solid-state fermentation with substrate based on peat/vermiculite/lentil meal was 10-fold higher than with substrate based on peat/vermiculite or in liquid fermentation. Conidial production under these conditions was maintained in the range of 10(8) conidia g(-1) substrate from 10 to 150 days after inoculation. Germinability of these conidia was >90%. Addition of other nutrients than lentil meal to peat/vermiculite did not enhance production of conidia. Presence of peat in the substrate was necessary for good conidia production, but change in the kind of peat or vermiculite did not improve conidial production. Conidial production was similar when the substrate was inoculated with 10(5), 10(6) or 10(7) conidia g(-1) dry substrate. Incubation of bags in light conditions did not enhance conidial production. Fresh conidia produced in this solid-state fermentation system reduced the incidence and lesion diameter induced by M. laxa on peaches.     

Daily green tea extract supplementation reduces prothrombotic and inflammatory states in dialysis patients

Cardiovascular disease (CVD) remains the most common cause for excess morbidity and mortality in patients with chronic kidney disease (CKD) and end stage renal disease (ESRD) under chronic dialysis. ESRD patients have increased oxidative stress and endothelial dysfunction alongside increased levels of inflammation related proteins, which has prompted the exploration of anti-inflammatory and antioxidant treatments to improve outcomes. As green tea is increasingly well recognized for its antioxidant properties, we probed the effect of consumption of 1 capsule daily of green tea as a commercially available, decaffeinated green tea capsule (1 g, catechin content 68 mg) for 6 months on fibrinogen and inflammation in dialysis patients. Chronic hemodialysis patients (N = 25) were recruited and fibrinogen, FDP-D-dimer, high sensitivity (hs) CRP and the mononuclear cell protein expression of p22^phox, were assessed before, i.e. baseline and after 6 months of ingestion of 1 green tea capsule per day. After 6 months of daily green tea capsule ingestion, dialysis patients showed reduced protein expression of p22^phox (p < 0.0001), reduced hsCPR (p = 0.032) and fibrinogen (p = 0.022) levels and increased FDP-D-dimer (p = 0.0019) compared to their values at baseline. These results document lower oxidative stress and inflammation with green tea capsule ingestion and suggest a likely positive impact of green tea treatment on the atherosclerotic process of ESRD patients under dialysis.     

A consumer study of fresh juices containing berry fruits

BACKGROUND: Consumer science techniques are proposed here to support the development of innovative fresh juices designed to exploit the sensory characteristics and nutritional advantages of berry fruits and to meet the needs of modern consumers, who increasingly buy ‘ready to eat’ products to save time, without abandoning a healthy diet. RESULTS: A series of consumer tests were conducted on 25 juices created by mixing one of the five berry fruits investigated with five different base juice variants. A high content of polyphenols and anthocyanins characterises these mixes, especially those based on pomegranate. Independently of the added berry fruit, the most successful recipes were the mixes with pineapple and blood orange, characterised by a ‘balanced’ proportion of sweet and sour components whereas the least appreciated were those based on pomegranate. Consumer habits and opinions were also recorded and consumer groups were identified by clustering variables: age, education and juice consumption were shown to be important factors in consumer choice. CONCLUSIONS: This study provides a useful insight into production and marketing strategies for a new juice line that could be accompanied by the key message: ‘Just fresh fruit: all the pleasure and nutritional intake of fresh fruit in an appealing drink’. Copyright © 2009 Society of Chemical Industry     

Nucleation and plasticization with recycled low-molecular-weight poly-3-hydroxybutyrate toughens virgin poly-3-hydroxybutyrate

Poly-3-hydroxybutyrate (PHB) is a widely distributed carbon storage molecule in prokaryotes and can serve as a biodegradable plastic replacement. However, the handling and material properties of virgin PHB are not as robust as some traditional petroleum-based plastics. Additives can be added to PHB to improve its qualities, but these additives are themselves often not biobased. A strategy was developed to utilize lower molecular weight PHB fragments derived from the recycling process as biobased additives. To simulate recycling, PHB was thermolyzed at elevated temperatures, and this degraded PHB (dPHB) was reactively processed with virgin PHB. Incorporation of dPHB nucleated and plasticized the virgin PHB as evidenced by increased crystallization temperature and crystallinity as well as decreased melt viscosity, stiffness, and melting temperature. Additionally, samples containing dPHB had increased toughness. Processing with dPHB decreased M_n, had little effect on M_w, and increased the Z-average molecular weight, indicating branching. These results demonstrate a route for nucleating, plasticizing, and toughening virgin PHB by using recycled PHB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47432.     

Analysis of Traffic-Induced Vibrations in a Cable-Stayed Bridge. Part II: Numerical Modeling and Stochastic Simulation

This paper describes the development of a numerical model to simulate the dynamic response of the bridge–vehicle system of Salgueiro Maia cable-stayed bridge, using the results from an extensive experimental investigation to calibrate this model. Further, a set of stochastic Monte Carlo simulations of the bridge–vehicle dynamic response is also presented, with the purpose of evaluating dynamic amplification factors, taking into account the randomness of different factors associated to characteristics of the pavement, of the vehicles and of the traffic flow.     

Electrical conductivity measurements and the nonhomogeneous settling behavior of aqueous suspensions of barite

Using electrical conductivity measurements to monitor the local concentration of solids indirectly in settling tests is a practice already explored in the literature. However, since suspended particles may comprise a mixture of solids, a new suspension preparation methodology and calibration procedure were proposed to eliminate the influence of soluble materials on conductivity measurements. This article investigates water-barite suspensions of 10%, 15%, and 20% v/v in solids. Their settling dynamics resulted in particle Reynolds numbers and Peclet numbers always smaller than 0.0012 and larger than 2100, respectively. Particle agglomeration, multiple boundaries (layers of different maximum local concentrations), channeling (formation of flow paths or channels), and particulate stratification were some phenomena inferred from the results. Hence, this article illustrates that settling behaviors typically seen in solid–liquid mixtures of non-Newtonian continuous phase can also occur in aqueous suspensions, indicating there are still considerable challenges to understanding the process of gravitational settling.     

On the SQH Method for Solving Differential Nash Games

Journal of Dynamical and Control Systems - A sequentialquadratic Hamiltonian schemefor solving open-loop differential Nash games is proposed and investigated. This method is formulated in the...