Model-Reference Adaptive Control of Distributed Lagrangian Infinite-Dimensional Systems Using Hamiltons Principle

This paper presents a Hamilton's principle for distributed control of infinite-dimensional systems modeled by a distributed form of the Euler-Lagrange method. The distributed systems are governed by a system of linear partial differential equations in space and time. A generalized potential energy expression is developed that can capture most physical systems including those systems that have no spatial distribution. The Hamilton's principle is applied to derive distributed feedback control methods without resorting to the standard weak-form discretization approach to convert an infinite-dimensional systems to a finite-dimensional systems. It can be shown by the principle of least action that the distributed control synthesized by the Hamilton's principle is a minimum-norm control. A model-reference adaptive control framework is developed for distributed Lagrangian systems in the presence of uncertainty. The theory is demonstrated by an application of adaptive flutter suppression control of a flexible aircraft wing

Rhizobacteria-mediated Induced Resistance in Barley against Cochliobolus sativus under Field Conditions

The effect of four rhizobacterial strains on the severity of spot blotch disease caused by cochliobolus sativus was evaluated for two growing seasons under rainfed conditions. Three barley genotypes were used as host plant. All strains reduced C. sativus severity, with effect more pronounced when Pseudomonas putida BTP1 and Bacillus subtilis Bs2508 were used. The disease reduction was up to 56% in Arabi Abiad / P. putida BTP1. The grain yield was not obviously affected by the presence of the rhizobacteria, except some signifitive increase in season 2. Raising the resistance by soaking seed with rhizobacterial strains might be of ultimate value in agriculture

Viability and pathogenicity of Rhynchosporium secalis after long-term storage

Long-term storage of Rhynchosporium secalis cultures is a challenge for any lab managing a working collection of isolates. In this work, the viability and pathogenicity of R. secalis stock cultures were tested after four years of storage at −20 °C in different concentrations of glycerol. Germinability were measured after each storage by collecting spores by coverslips and placing them on water agar in closed Petri dishes at 20–22 °C in the dark and allowed to germinate for 24 h. Additionally, at the end of each storage treatment, conidia were collected by coverslips from sporulated leaf lesions of symptomatic barley leaves and placed under similar conditions as non-stored controls. Cultures of all stored isolates were viable with a spore germination rate of 72.28% (Rs22) after four years of storage at −20 °C in 60% glycerol. Low viability and contamination were observed when spores were stored in sterile distilled water and in Lima bean agar. All isolates continued to infect barley leaves after 4 years of storage. However, the pathogenicity was significantly (P <0.05) reduced in isolates stored in glycerol as compared with controls. This work helps to preserve R. secalis for a long term period at −20 °C without any contamination; therefore, due to the low costs our results could be applicable for laboratories that have limited resources

Mycorrhizal Application as a Biocontrol Agent against Common Root Rot of Barley

This study was conducted to assess the biocontrol efficacy of vesicular arbuscular mycorrhizae (VAM) against barley common root rot caused by Cochliobolus sativus. Mycorrhization of barley was achieved by growing the plants in expanded clay mixed with 10% (v/v) VAM fungus inoculum in pots experiments. Large differences in disease reactions were observed among genotypes and among treatments. VAM treatments significantly reduced the percentage of disease severity in infected barley plants and increased significantly root biomass, which could be attributed to enhanced nutrients uptake, via an increase in the absorbing surface area. It can be concluded that the application of VAM as a biocontrol agent played an important role in plant resistance and exhibit greater potential to protect barley plants against C. sativus

Output Feedback Adaptive Control of Non-Minimum Phase Systems Using Optimal Control Modification

This paper describes output feedback adaptive control approaches for non-minimum phase SISO systems with relative degree 1 and non-strictly positive real (SPR) MIMO systems with uniform relative degree 1 using the optimal control modification method. It is well-known that the standard model-reference adaptive control (MRAC) cannot be used to control non-SPR plants to track an ideal SPR reference model. Due to the ideal property of asymptotic tracking, MRAC attempts an unstable pole-zero cancellation which results in unbounded signals for non-minimum phase SISO systems. The optimal control modification can be used to prevent the unstable pole-zero cancellation which results in a stable adaptation of non-minimum phase SISO systems. However, the tracking performance using this approach could suffer if the unstable zero is located far away from the imaginary axis. The tracking performance can be recovered by using an observer-based output feedback adaptive control approach which uses a Luenberger observer design to estimate the state information of the plant. Instead of explicitly specifying an ideal SPR reference model, the reference model is established from the linear quadratic optimal control to account for the non-minimum phase behavior of the plant. With this non-minimum phase reference model, the observer-based output feedback adaptive control can maintain stability as well as tracking performance. However, in the presence of the mismatch between the SPR reference model and the non-minimum phase plant, the standard MRAC results in unbounded signals, whereas a stable adaptation can be achieved with the optimal control modification. An application of output feedback adaptive control for a flexible wing aircraft illustrates the approaches

Salicylic acid pathway changes in barley plants challenged with either a biotrophic or a necrotrophic pathogen

The biotrophic Blumeria graminis (Bg) and the necrotrophic Cochliobolus sativus; (Cs) are economically important fungal pathogens of barley globally. To better understand barley mechanisms to resist these pathogens, changes in salicylic acid (SA) and its responsive genes particularly the pathogenesis related PR1, PR2, PR3 and PR5 were evaluated using qRT-PCR across four time points post infection. Data showed that SA contents significantly increased (P = 0.001) in infected plants of both resistant and susceptible genotypes 24 h post inoculation in comparison with non-infected controls. In addition, time-course tests revealed a notable contradiction in the defense-related genes expression patterns between barley and Bg and Cs interactions, showing that expression patterns of the same defense-associated genes were altered in adaptation to different pathogens. PR1 and PR2 genes were highlyactivated inresistant plants infected with the necrotrophic pathogen Cs rather than of the biotrophic one. The uniformity in barley defense response mechanisms could be in convention with the well-accepted notion that these responses are high intense in the resistant genotype. Our work provides useful information on the expected role of SA pathways in barley towards biotrophic and necroptrophic pathogens with different lifestyles

Salicylic acid and hydrogen peroxide accumulation in relation to hydrolyte leakage in barley plants challenged with Cochliobolus sativus

Spot blotch (SB) caused by the hemibiotrophic fungal pathogen Cochliobolus sativus is a destructive disease of barley worldwide. To better understand the mechanisms of resistance to this disease, the involvements of salicylic acid (SA), hydrogen peroxide (H2O2) and ion fluxes during the interaction between resistant and susceptible barley seedlings and C. sativus were investigated. Early SA accumulation in leaf tissues was accompanied with an increase in H2O2 concentration in both compatible and incompatible interactions. The resistant cultivar constitutively contained higher levels of H2O2 and SA, as well as during the 72 h as compared with the un-infected control (0 h). However, levels increased rapidly upon infection in both cultivars. Moreover, a markedly greater increase in ion fluxes from the compatible material compared with the incompatible one was observed. Results suggest that SA and H2O2 accumulation are important during both compatible and incompatible barley- C. sativus interactions

A facile and green synthetic approach toward fabrication of alcea- and thyme-stabilized tio2 nanoparticles for photocatalytic applications

A facile and green synthetic approach was considered for the synthesis of stabilized titanium dioxide (TiO2) nanoparticles. Extracts of Alcea and Thyme plants were used to synthesis TiO2 nanoparticles for photocatalytic applications. Evaluation of the structural and phase formation via X-ray diffraction (XRD) indicated the formation of the anatase phase of TiO2 along with the rutile phase. A desired single phase of anatase was obtained upon heating the as-synthesized samples at 500 °C for 3 h. Using the information provided by the XRD analyzer and the Debye Scherer relationship, the average crystallite size was found to be around 6 and 10 nm for the samples synthesized using Alcea and Thyme plants, respectively. To determine the elemental analysis and chemical structure, the energy dispersive X-ray (EDX) analyzer and Fourier Transform Infrared (FTIR) spectroscopy were employed. Field emission scanning electron microscopy (FESEM) indicated batches of ultrafine agglomerated particles for both samples, which their sizes grew by the heating process. The UV–visible analysis of photocatalytic properties confirmed the priority of TiO2 nanoparticles prepared with Thyme extracts

Transcriptome profile of early responsive genes in susceptible barley during Rhynchosporium secalis infection

Scald caused by Rhynchosporium secalis, is an economically important disease found worldwide. In order to profile genes and pathways responding to R. seclais infection, leaf transcriptomes before and after fungus inoculation in susceptible barley were compared using cDNA-AFLP technique. Transcriptional changes of 144 expressed sequence tags (ESTs) were observed, of which 18 have no previously described function. Functional annotation of the transcripts revealed a wide range of pathways including cell wall fortification, cytoskeleton construction and metabolic processes at different time points. Furthermore, the results of RT-PCR analysis on candidate genes, ABC transporters and lycine-specific demethylase were consistent with the cDNA-AFLP data in their expression patterns. Taken together, our data suggest that susceptible barley reprograms metabolic and biological processes to initiate a suitable response R. secalis infection