Mycorrhizal Inoculation Improves Plant Growth and Yield of Micropropagated Early Globe Artichoke under Field Conditions

The micropropagation appears to be a valid alternative method for the production of large-scale, phenotypically homogeneous, and disease-free plants, particularly for spring globe artichoke genotypes. Nevertheless, micropropagated plants have some problems during the acclimatization in field environments. The inoculation with arbuscular mycorrhizal fungi appeared to overcome the transplanting stress. Therefore, a comparison was drawn between the field performances of different vegetative propagation techniques (micropropagated/mycorrhized and offshoots cultivation) of early globe artichoke clones over two growing seasons. The micropropagation/mycorrhization appeared to deliver a better field performance in terms of both plant growth and productivity traits as compared with offshoots cultivated. In particular, the micropopagated/mycorrhized plants exhibited the highest vegetative growth values than the offshoots of the cultivated ones, such as the plant height and the main floral stem length. The micropopagated/mycorrhized plants were also more productive, exceeding the head yield of offshoots cultivated ones by about 63%. However, the micropopagated/mycorrhized plants accumulated almost a month late on the first harvest respect to offshoots cultivated ones. Our data also showed that the effects of the new proposed propagation method were genotype- and season-dependent. Accordingly, some plant growth and productivity traits showed significant ‘propagation method × genotype’ and ‘propagation method × growing season’ interaction. This study revealed that the micropropagation, as well as the mycorrhization, could represent an efficient and sustainable cropping system to reintroduce and increase the productivity of autochthons landraces.

Field performance of four vibrating-wire piezometer installation methods

Vibrating wire piezometers provide a number of advantages over the traditional hydraulic piezometer design. There are currently many methods and configurations for installing vibrating-wire piezometers, the most common being: single piezometers in sand packs (SP), multilevel piezometers in sand packs (MLSP), and fully-grouted multilevel piezometers using either bentonite (FGB) or cement-bentonite grout (FGCB). This study assesses the performance of these four different installation methods at a field site possessing complex stratigraphy, including glacial and marine sediments. To accomplish this objective, pore pressure data recorded between December 2017 and July 2019 were analyzed. Data indicate that SP, MLSP, and FGB piezometers performed most reliably, based on the fact that piezometers installed at the same depth with these methods recorded similar pressure variations that were coherent with the hydrogeological setting. Of the two fully-grouted installations using cement-bentonite grout, one installation failed completely due to a hydraulic short circuit, likely caused by preferential flow occurring along the wires of the embedded instruments. The lack of a standard method for mixing cement-bentonite grout at the time of construction likely contributed to the failure of the FGCB installations, as the grout mixture used in this study was likely too viscous to provide a suitable seal.

Improved-Efficacy EM-Based Antenna Miniaturization by Multi-Fidelity Simulations and Objective Function Adaptation

The growing demand for the integration of surface mount design (SMD) antennas into miniaturized electronic devices has imposed increasing limitations on the structure dimensions. Examples include embedded antennas in applications such as on-board devices, picosatellites, 5G communications, or implantable and wearable devices. The demands for size reduction while ensuring a satisfactory level of electrical and field performance can be managed through constrained numerical optimization. The reliability of optimization-based size reduction requires utilization of full-wave electromagnetic (EM) analysis, which entails significant computational costs. This can be alleviated by incorporating surrogate modeling techniques, adjoint sensitivities, or the employment of sparse sensitivity updates. An alternative is the incorporation of multi-fidelity simulation models, normally limited to two levels, low and high resolution. This paper proposes a novel algorithm for accelerated antenna miniaturization, featuring a continuous adjustment of the simulation model fidelity in the course of the optimization process. The model resolution is determined by factors related to violation of the design constraints as well as the convergence status of the algorithm. The algorithm utilizes the lowest-fidelity model for the early stages of the optimization process; it is gradually refined towards the highest-fidelity model upon approaching convergence, and the constraint violations improve towards the preset tolerance threshold. At the same time, a penalty function approach with adaptively adjusted coefficients is applied to enable the precise control of constraints, and to increase the achievable miniaturization rates. The presented procedure has been validated using five microstrip antennas, including three broadband, and two circularly polarized structures. The obtained results corroborate the relevance of the implemented mechanisms from the point of view of improving the average computational efficiency of the optimization process by 43% as compared to the single-fidelity adaptive penalty function approach. Furthermore, the presented methodology demonstrates a performance that is equivalent or even superior to its single-fidelity counterpart in terms of an average constraint violation of 0.01 dB (compared to 0.03 dB for the reference), and an average size reduction of 25% as compared to 25.6%.

Proposed Changes to Asphalt Binder Specifications to Address Binder Quality-Related Thermally Induced Surface Damage

Superpave specifications address binder properties that may lead to rutting, transverse cracking, and fatigue damage with varying degrees of success. However, asphalt binder production and formulation has significantly changed and introduced much more variability in relation to quality since the development of the Superpave Performance-Grade system because of economic, technical, and environmental reasons. Consequently, aged-induced surface distresses under combined thermal and traffic loading have become the main challenge for highway agencies. Thermally induced surface deterioration appears in the form of traditional transverse cracking, block cracking, and raveling, or accelerating damage at construction joints. This study evaluated the limitations of the proposed linear viscoelastic (LVE) rheological cracking surrogates, such as ΔTc, R-value, and G-R parameters, and the ability of the Asphalt Binder Cracking Device (ABCD) failure test to overcome these limitations. ABCD is particularly appropriate to rank binder performance because the measured cracking temperature (Tcr) encompasses binder LVE properties, failure strength, coefficient of thermal contraction, and cooling rate. The proposed parameter (ΔTf = Tc(S = 300 MPa) from BBR—Tcr from ABCD) relates the failure temperature to the equi-stiffness temperature and gives credit to well-formulated and compatible polymer-modified binders expected to increase binder strength and strain tolerance. This paper proposes a specification framework based on both ΔTc and ΔTf, universally applicable, regardless of binder composition. Additionally, preliminary purchase specification limits for binders used in surface layers are proposed based on the analysis of 44 binders, 15 with corresponding field performance data. Obviously, as confirmed by a recent stakeholder workshop and industry feedback, these preliminary specification limits need further validation and possible adjustments to account for regional experience and local challenges.

Development of VUMAT and VUHARD Subroutines for Simulating the Dynamic Mechanical Properties of Additively Manufactured Parts

Numerical modelling and simulation can be useful tools in qualification of additive manufactured parts for use in demanding structural applications. The use of these tools in predicting the mechanical properties and field performance of additive manufactured parts can be of great advantage. Modelling and simulation of non-linear material behaviour requires development and implementation of constitutive models in finite element analysis software. This paper documents the implementation and verification process of a microstructure-variable based model for DMLS Ti6Al4V (ELI) in two separate ABAQUS/Explicit subroutines, VUMAT and VUHARD, available for defining the yield surface and plastic deformation of materials. The verification process of the implemented subroutines was conducted for single and multiple element tests with varying prescribed loading conditions. The simulation results obtained were then compared with the analytical solutions at the same conditions of strain rates and temperatures. This comparison showed that both developed subroutines were accurate in predicting the flow stress of various forms of DMLS Ti6Al4V (ELI) under different conditions of strain rates and temperatures.

Field Performance Evaluation of High Polymer-Modified Asphalt Concrete Overlays

The objective of this paper was to assess the viability of using high polymer (HP) modified asphalt concrete (AC) mixtures in Virginia as a reflective crack mitigation technique or when deemed appropriate as a tool for increased crack resistance on higher volume facilities. This was achieved by compiling and evaluating routine distress survey data against pre-paving distress survey data for relevant in-service HP pavements constructed between 2015 and 2018 and comparing them with several control in-service conventional polymer-modified asphalt (PMA) pavements. This is the first effort in North America to provide a detailed field performance of HP AC mixtures. In general, none of the evaluated mixtures (HP or PMA) was able to prevent reflective cracking completely. The HP sections showed the most promising performance 5 years after construction regardless of traffic level and the pre-existing pavement conditions. The pavement management system data for the reviewed sections indicated a potential controlling effect of the joint condition of the underlying jointed concrete pavement layer regardless of the asphalt mixture type employed (PMA or HP). Moreover, performance evaluations using the network-level pavement management data were conducted to estimate the life expectancy of HP AC overlays. Two different approaches and three levels of analysis were undertaken. Overall, PMA and HP AC overlays had an average predicted service life of 6.2 and 8.3 years, respectively, indicating a 34% extension of performance life of the AC overlays with high polymer modification.

Different Sweet Orange–Rootstock Combinations Infected by Candidatus Liberibacter asiaticus under Greenhouse Conditions: Effects on the Scion

The devastating citrus disease huanglongbing (HLB) associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas) has caused a more than 70% reduction in citrus production since its discovery in Florida in 2005. Most citrus scion cultivars are sensitive to HLB, whereas some cultivars used as rootstocks are tolerant. Using such tolerant rootstocks can help trees to cope better with the disease’s impact. Evaluating rootstock effects on a grafted scion in the field takes many years, but shorter-term evaluation is imperative to aid in rootstock selection for an HLB-endemic production environment. In this study, we investigated grafted healthy and CLas-infected citrus trees under controlled greenhouse conditions. The objectives were to identify traits suitable for assessing grafted tree tolerance in advance of longer-term field studies and aiding in the selection of superior rootstock cultivars. We assessed 10 commercially important rootstocks grafted with ‘Valencia’ sweet orange scion and with known field performance. At 6, 9, 15, and 21 months after graft inoculation (mai), leaf CLas titers were determined and canopy health was evaluated. Plants were destructively sampled at 21 mai to assess plant biomasses and other physiological and horticultural variables. There was little influence of the rootstock cultivar on CLas titers. Surprisingly, few HLB foliar disease symptoms and no differences in soluble and nonsoluble carbohydrate concentrations were measured in infected compared with healthy plants, despite high CLas titers and significant reductions in plant biomasses. Most trees on rootstocks with trifoliate orange parentage were less damaged by HLB than other rootstocks, although results did not always agree with reported field performance. Among the different variables measured, leaf size appeared to be most predictive for grafted tree assessment of HLB sensitivity. The results of this study provide a better understanding of the strengths and weaknesses of assessing rootstock influence on grafted tree performance in a controlled greenhouse environment. Although such studies provide valuable information for cultivar tolerance to HLB, other rootstock traits will ultimately contribute to field survival and productivity in an HLB endemic production environment.

Different Sweet Orange‒Rootstock Combinations Infected by Candidatus Liberibacter asiaticus under Greenhouse Conditions: Effects on the Roots

Grafting a scion onto a rootstock results in physical and physiological changes in plant growth and development, which can affect tree vigor, productivity, and tolerance to stress and disease. Huanglongbing (HLB) is one of the most destructive citrus diseases and has become endemic in Florida since its introduction in 2005. It is associated with the phloem-limited bacteria Candidatus Liberibacter asiaticus (CLas), which cause severe metabolic disruptions in affected plants. Although most scion cultivars are highly susceptible, some rootstock cultivars are tolerant and allow the grafted tree to cope better with the disease. The objectives of this study were to identify rootstock traits that can be used to assess cultivars under controlled greenhouse conditions in advance of longer-term field trials. We used 10 commercially important rootstocks with different genetic backgrounds and known field performance in graft combination with ‘Valencia’ sweet orange scion. Trees were graft-inoculated with CLas and compared against mock-inoculated trees. Tree health and CLas populations were assessed regularly, and root growth was monitored using a minirhizotron imaging system. Plants were excavated and destructively sampled 21 months after inoculation to assess biomass distributions and other CLas-induced effects. We found significant differences between healthy and infected trees for most variables measured, regardless of the rootstock. In contrast to leaf CLas titers, root titers were significantly influenced by the rootstock, and highest levels were measured for ‘Ridge’ sweet orange and sour orange. Root growth and root biomasses were reduced upon infection but differences among rootstocks did not always agree with reported field performances. Despite severe biomass reductions plants maintained their relative distribution of biomass among different components of the root system, and no dead roots were observed. Root respiration was reduced by CLas infection and was overall higher in tolerant cultivars suggesting its potential as a physiological marker. This study improves our knowledge about the strengths and weaknesses of assessing rootstock traits of grafted trees in a controlled greenhouse setting. Results from the study suggest that in addition to HLB tolerance, other rootstock traits will ultimately have major contributions to field survival and productivity of the grafted trees in an HLB endemic production environment.

Approaches to forecast oil field performance at the well pads level and beta testing on oilfields of RN-Nyaganneftegaz (ROSNEFT)

Background. The study performed by Rosneft employees shown in this paper demonstrates approach and analytical methods that allows to forecast oil production at the level of minimal infrastructure units. These approaches are used to forecast long-term oil production and predict infrastructure blockage. The approach was partially automated by the authors. This made it possible to testing at giant Krasnoleninskoye oilfield. Aim. The study was performed in order to develop and test an approaches to forecast oil production of large oil fields with high detail levels. Materials and methods. Common methods of decline curve analysis and water-into-oil curve analysis were used in this work to analyze the precondition. The main feature of the approach is the analysis of precondition at the level of large well clusters and transfer it to the level of wells. Some of the actions were automated by new proprietary software and were tested at the giant brown field. The software was integrated with the corporate database. Results. An author’s approach has been developed. The approach allows to forecast oil production at the level of infrastructure units using analytical methods. Oil production of the giant brown field with high detail levels were forecasted using the proposed approaches and developed software. Conclusions. The results show that the developed approaches and software can be used to forecast mediumand long-term performance of producing oil fields in the conditions of existing external and infrastructural constraints.