Thermographic non-destructive inspection of wind turbine blades using unmanned aerial systems

Abstract

Wind turbines are gaining importance in the last years because of their high efficiency during energy production without greenhouse gas emission. Furthermore, they can be installed both on- and off-shore. However, wind blade maintenance operations have become difficult and expensive due basically to size aspects and operative costs related with their location and out-off service period. A non-destructive technique capable of detecting most significant in service defects in composite wind blade is infrared thermography (IRT). However, this method can only be applied by developing cost efficient in situ inspection strategies. This work presents a feasibility study for defect detection during maintenance operations in wind blades using unmanned aerial systems (UASs). IRT inspections are performed by means of passive IRT methodology first (i) for specimen located at the ground level with artificial defects (like delaminations, cracks, impact damage and debondings) and later (ii) during flight operation using an rotorcraft UAS. The developed inspection strategies, test results and several features of the developed acquisition system are reported.     

化工分离课程试题库编制与软件开发

为便于学校和教师能够对教与学的效果进行科学考察和实施教考分离,我们编制了化工分离课程试题库软件。本文介绍了该试题库软件编制的作用、方法与步骤。根据有关试题库建设的理论,讨论了试题库软件设计与实现的主要环节,说明了试题库参数的优化、试卷组织算法与策略的实现过程。     

Genomic Architecture of Phenotypic Plasticity in Response to Water Stress in Tetraploid Wheat

Phenotypic plasticity is one of the main mechanisms of adaptation to abiotic stresses via changes in critical developmental stages. Altering flowering phenology is a key evolutionary strategy of plant adaptation to abiotic stresses, to achieve the maximum possible reproduction. The current study is the first to apply the linear regression residuals as drought plasticity scores while considering the variation in flowering phenology and traits under non-stress conditions. We characterized the genomic architecture of 17 complex traits and their drought plasticity scores for quantitative trait loci (QTL) mapping, using a mapping population derived from a cross between durum wheat (Triticum turgidum ssp. durum) and wild emmer wheat (T. turgidum ssp. dicoccoides). We identified 79 QTLs affected observed traits and their plasticity scores, of which 33 reflected plasticity in response to water stress and exhibited epistatic interactions and/or pleiotropy between the observed and plasticity traits. Vrn-B3 (TaTF1) residing within an interval of a major drought-escape QTL was proposed as a candidate gene. The favorable alleles for most of the plasticity QTLs were contributed by wild emmer wheat, demonstrating its high potential for wheat improvement. Our study presents a new approach for the quantification of plant adaptation to various stresses and provides new insights into the genetic basis of wheat complex traits under water-deficit stress.     

药物化学试题库在独立学院的实践与思考

试题库是实现教考分离提高教学质量的重要手段,独立学院建立试题库具有重要意义。文章通过教学实践,分析了《药物化学》试题库的建设方法以及应用。     

Comparing protein sequence-based and predicted secondary structure-based methods for identification of remote homologs

We have compared a novel sequence–structure matching technique,FORESST, for detecting remote homologs to three existing sequencebased methods, including local amino acid sequence similarityby BLASTP, hidden Markov models (HMMs) of sequences of proteinfamilies using SAM, HMMs based on sequence motifs identifiedusing meta-MEME. FORESST compares predicted secondary structuresto a library of structural families of proteins, using HMMs.Altogether 45 proteins from nine structural families in thedatabase CATH were used in a cross-validated test of the foldassignment accuracy of each method. Local sequence similarityof a query sequence to a protein family is measured by the highestsegment pair (HSP) score. Each of the HMM-based approaches (FORESST,MEME, amino acid sequence-based HMM) yielded log-odds scorefor the query sequence. In order to make a fair comparison amongthese methods, the scores for each method were converted toZ-scores in a uniform way by comparing the raw scores of a queryprotein with the corresponding scores for a set of unrelatedproteins. Z-Scores were analyzed as a function of the maximumpairwise sequence identity (MPSID) of the query sequence tosequences used in training the model. For MPSID above 20%, theZ-scores increase linearly with MPSID for the sequence-basedmethods but remain roughly constant for FORESST. Below 15%,average Z-scores are close to zero for the sequence-based methods,whereas the FORESST method yielded average Z-scores of 1.8 and1.1, using observed and predicted secondary structures, respectively.This demonstrates the advantage of the sequence–structuremethod for detecting remote homologs.     

An Uncleaved Signal Peptide Directs the Malus xiaojinensis Iron Transporter Protein Mx IRT1 into the ER for the PM Secretory Pathway

Malus xiaojinensis iron-regulated transporter 1 (Mx IRT1) is a highly effective inducible iron transporter in the iron efficient plant Malus xiaojinensis. As a multi-pass integral plasma membrane (PM) protein, Mx IRT1 is predicted to consist of eight transmembrane domains, with a putative N-terminal signal peptide (SP) of 1–29 amino acids. To explore the role of the putative SP, constructs expressing Mx IRT1 (with an intact SP) and Mx DsIRT1 (with a deleted SP) were prepared for expression in Arabidopsis and in yeast. Mx IRT1 could rescue the iron-deficiency phenotype of an Arabidopsis irt1 mutant, and complement the iron-limited growth defect of the yeast mutant DEY 1453 (fet3fet4). Furthermore, fluorescence analysis indicated that a chimeric Mx IRT1-eGFP (enhanced Green Fluorescent Protein) construct was translocated into the ER (Endoplasmic reticulum) for the PM sorting pathway. In contrast, the SP-deleted Mx DsIRT1 could not rescue either of the mutant phenotypes, nor direct transport of the GFP signal into the ER. Interestingly, immunoblot analysis indicated that the SP was not cleaved from the mature protein following transport into the ER. Taken together, data presented here provides strong evidence that an uncleaved SP determines ER-targeting of Mx IRT1 during the initial sorting stage, thereby enabling the subsequent transport and integration of this protein into the PM for its crucial role in iron uptake.     

Drug complexation and physicochemical properties of vinylpyrrolidone‐N,N′‐dimethylacrylamide copolymers

Solid dispersions of the nonsteriodal antiinflammatory drug (NSAID) 2′,4′‐difluoro‐4‐hydroxy‐(1,1′‐biphenyl)‐3‐carboxylic acid (DIF) with the water‐soluble random copolymer poly(N‐vinyl‐2‐pyrrolidone‐co‐N,N′‐dimethylacrylamide) (VP‐co‐DMAm) were prepared by the solvent method (coevaporates) and melting DIF/VP‐co‐DMAm (cofused) physical mixtures. Differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and X‐ray diffraction (XRD) were used to elucidate the possible interaction between the NSAID drug and VP‐co‐DMAm in cofused and coevaporated polymer–drug solid dispersions. The XRD and FTIR studies suggest the presence of physical interactions with formation of a charge transfer complex between DIF and the VP‐co‐DMAm copolymers as a consequence of the coevaporation or cofusion processes. In solution, dynamic and equilibrium solubility studies were determined to elucidate the mechanism of interaction between DIF and VP‐co‐DMAm copolymers. Thermodynamics data about the DIF: VP‐co‐DMAm dissolution process indicate that the coevaporated systems are more stable that the cofused systems. The dissolution of the cofused and coevaporated systems was diffusion controlled and the dissolution kinetics followed the Noyes–Whitney and the Levich equations. Molecular simulations using semiempirical quantum chemical calculations reinforce the experimental results, suggesting that the improvement in the DIF solubility could be attributed to the charge transfer complex formation between the drug and VP‐co‐DMAm copolymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1337–1347, 2004     

Optimal multi-floor process plant layout

This paper presents a general mathematical programming formulation for the multi-floor process plant layout problem, which considers a number of cost and management/engineering drivers within the same framework thus resolving various trade-offs at an optimal manner. The proposed model determines simultaneously the number of floors, land area, floor allocation of each equipment item and detailed layout for each floor. The overall problem is formulated as a mixed integer linear programming (MILP) model based on a continuous domain representation. The applicability of the model is demonstrated by three illustrative examples.     

Improvement of Major Depression is Associated with Increased Erythrocyte DHA

The aim of this study was to determine if changes in omega‐3 polyunsaturated fatty acid status following tuna oil supplementation correlated with changes in scores of depression. A total of 95 volunteers receiving treatment for major depression were randomised to consume 8 × 1 g capsules per day of HiDHA (2 g DHA, 0.6 g EPA and 10 mg Vitamin E) or olive oil (placebo) for 16 weeks, whilst undergoing weekly counseling sessions by trained clinical psychologists using a standard empirically validated psychotherapy. Depression status was assessed using the 17 item Hamilton rating scale for depression and the Beck Depression Inventory by a psychodiagnostician who was blind to the treatment. Blood was taken at baseline and 16 weeks (n = 48) for measurement of erythrocyte fatty acids. With HiDHA supplementation, erythrocyte DHA content rose from 4.1 ± 0.2 to 7.9 ± 0.4 % (mean ± SEM, p < 0.001) of total fatty acids but did not change (4.0 ± 0.2 to 4.1 ± 0.2 %) in the olive oil group. The mean changes in scores of depression did not differ significantly between the two groups (?12.2 ± 2.1 for tuna oil and ?14.4 ± 2.3 for olive oil). However, analysis of covariance showed that in the fish oil group there was a significant correlation (r = ?0.51) between the change in erythrocyte DHA and the change in scores of depression (p < 0.05). Further study of the relationship between DHA and depression is warranted.     

Application of infrared thermography to adhesion science

Infrared thermography (IRT) is a non-contact, non-intrusive technique which converts the invisible thermal energy, radiated from the surface of an object in the infrared band of the electromagnetic spectrum, into a video signal, each energy level being generally represented by a color or a gray level. IRT has been considered an exciting scientific breakthrough since its introduction in the early 1960s. Indeed, the new generation of fully-computerized infrared imaging systems can provide both qualitative and quantitative measurements which are useful in many industrial and research fields. Nevertheless, infrared thermography is still not completely exploited. The reason for this lies, in part, in the lack of knowledge, since at first sight IRT seems to be too expensive and difficult to use and, in part, in the industrial inertia to change the routine procedures. The aim of this review article is to provide the reader with a background to infrared theory and with an overview of the most relevant applications of IRT to the adhesion field. The use of IRT as a non-destructive evaluation technique with the two different approaches of pulse thermography (PT) and lock-in thermography (LT) is discussed. Many applications are described which involve several different materials (metals, plastics, plaster, composites, hybrid composites and sandwiches) and different types of bonds (coatings, sandwiches and joints). The results show that both PT and LT are able to detect material modifications caused by surface treatments, presence of inhomogeneities in bulk materials, as well as disbonding, delamination, and cracks and slag inclusions in bonded structures. The LT is also capable of evaluating materials characteristics (e.g., variations in density, porosity, hardness, etc., which induce variations in the phase angle), the dimension of the heat affected zone in welded joints, coating thickness, bondline thickness, the effects of adhesive thickness, the effects induced in bonded structures by substrate surface treatments, and the effects of crosslinking in polymers. The LT technique is particularly advantageous in the evaluation of frescoes, mosaics and antique artworks. The reported applications provide also information which is useful for decision making about the use of IRT alone, or combined with other techniques.     

化工建设项目施工阶段交工技术文件编制

在论述化工建设项目施工阶段交工技术文件编制规则的基础上,指出了该项工作中存在的实际问题及解决办法.     

Temperature dependence of crack initiation fracture toughness of various nanoparticles filled polyamide 66

In the present study, the crack initiation fracture toughness of various nanoparticles filled polyamide 66 was investigated in a broad temperature range (23-120 °C) by using an essential work of fracture (EWF) approach. Four types of spherical nanoparticles, i.e. two types of TiO₂ (21 nm, with/without surface modification), SiO₂ (13 nm) and Al₂O₃ (13 nm), were selected with a constant volume content of 1% in nanocomposites, which were compounded using a twin-screw-extruder. The addition of nanoparticles led to an enhanced specific EWF item at most test temperatures at the cost of the reduction of the non-EWF item. The value of the specific EWF was also estimated by a crack opening displacement method. Associated with SEM fractograph analysis, it was clear that two basic factors, i.e. crack tip blunting and net section stress, finally determined the EWF value. With the addition of nanoparticles, the item of crack tip blunting was increased at most temperature range, which may be incidental with the formation of numerous dimples and sub-dimples induced by nanoparticles; while the item of net section stress was correlated with the particle distribution, especially at room temperature, which was notably decreased in case of poor nanoparticle distribution.     

Experimental confirmation of some factors influencing dynamic concrete compressive strengths in high-speed impact tests

This paper reports probably the first systematic experimental investigation of the influences of lateral inertia confinement, end friction confinement and aggregates in high-speed impact tests on dynamic compressive properties of concrete. The influences of the concerned factors on the dynamic increase factor (DIF) are discussed. The proposed DIF relations in Hao and Hao [36] are verified by the experimental data in this study. The results confirm the observations made before based on numerical simulations that lateral inertia confinement effect is dependent on the specimen diameter and strain rate. The influences of aggregate size and volume to DIF are considerable, and aggregates cannot be neglected in experimental or numerical studies. It also confirms that the end friction confinement effect is sensitive to the specimen geometry and strain rate. The equation proposed in Hao et al. [40] based on numerical simulations satisfactorily removes the friction confinement effect on the DIF of concrete material strength obtained in impact test.     

IR-Thermography as a non-destructive tool to derive indirect information on the physical-mechanical behaviour of alkali activated materials

A combination of conventional and un-conventional methods is here used to assess the physical-mechanical properties of some alkaline activated pastes and mortars. The latter were purposely synthetized by using Etna ashes as precursor, whose suitability in the alkaline activation process has been ascertained by previous studies. Additionally, the potential reuse of the huge quantities of pyroclastic deposits released into the atmosphere during explosive volcanic eruptions represents an ambitious challenge for the local communities, other than being part of the “Ecological transition” topic promoted by the European Community. The physical-mechanical characterization of the experimental materials has been carried out by using: capillary water absorption test, infrared thermography (IRT), accelerated ageing test by salt mist, uniaxial compressive strength and drilling resistance test. The data obtained for pastes and mortars have been compared to each other and also with traditional materials commonly used in the building sector. The experimental results displayed a strong correlation between the rate of heat dispersion and the microstructure of the samples. In detail, the pastes show a more compact structure than mortars, which is responsible for a slower heat release and a lower capillary water absorption rate, as well as a better mechanical performance. IRT, used for the first time on these materials, revealed a high potential in providing feedback on other physical-mechanical features of alkali activated materials, commonly derived by using destructive methods.     

A new model in correlating and calculating the solid–liquid equilibrium of salt–water systems

In this work, a new activity coefficient model was deduced for the correlation of solid–liquid equilibrium(SLE) in electrolyte solutions. The new excess Gibbs energy equation for SLE contains two parts: the single electrolyte item and the mixed electrolyte item. Then a new hypothesis for the reference state of activity coefficients was proposed in the work. Literature data for single electrolyte solution and mixed electrolyte solution systems,with temperature spanning from 273.15 to 373.15 K, were successfully correlated using the developed model.     

催化分子氧氧化醇类的研究进展

综述了用氧气或空气（分子氧）作为化学计量氧化剂,在催化剂作用下氧化醇类的研究进展,并对某些代表性的催化氧化反应的特点和选择性进行了讨论。     

Application of holographic interference technique to mechanical studies of polymeric solids

Holographic reflective interference patterns arising from a small displacement of the surface of polymer solids provide a very sensitive means for detecting the internal stress related to molecular orientation, as well as measuring very small time dependent deformations not accessible by conventional means. Applicability of this technique using 6328Å laser light on various mechanical studies in polymeric solids is discussed.     

Genetic linkage methods for quantitative traits

We discuss methods for detecting genetic linkage for quantitative data. The usual LOD score method uses a pseudolikelihood formulation and has optimal power provided all parameters are correctly specified, but can lead to erroneous estimates of the location for the locus influencing a trait under misspecification of parameters describing the variance of the trait. Alternative methods, in which attention focuses upon modelling covariation among relatives as a function of genetic marker, similarity lead to unbiased estimates of the location and major gene heritability of the trait influencing locus. The Haseman-Elston approach uses a regression method to perform linkage analysis and its properties have been widely studied. This method is generally less powerful than variance components procedures, but the maximum likelihood-based variance components procedures require normality of the trait to ensure robustness of the genetic linkage tests (i.e. a correct false positive rate). When samples are non-randomly selected an ascertainment correction is generally required in order to obtain unbiased parameter estimates when applying variance components methods. For quantitative traits, ascertainment corrections usually condition either on the proband exceeding a threshold, or on the trait value of the proband. We summarize simulations that show that both approaches lead to similar efficiencies for estimating genetic effects. Finally, we discuss methods for analysing diseases that include time-to-onset information. A variety of methods are available for the linkage analysis of quantitative traits. Here, we have reviewed the most commonly used methods.     

Synthesis,Structure and Sensing Property of Novel Zinc(II) Framework with Mixed 3,3′,5,5′‐Tetra(1H‐imidazol‐1‐yl)biphenyl and 2,6‐Naphthalenedicarboxylate Ligands

With increasing use of antibiotics, it becomes more and more important for selectively and sensitively detecting antibiotics. In this work, a new Zn(II) framework [Zn₂(L)(NDC)(HCOO)₂] ? 2H₂O ( 1 ) was achieved by using organic ligands 3,3′,5,5′‐tetra(1H‐imidazol‐1‐yl)biphenyl (L) and 2,6‐naphthalenedicarboxylic acid (H₂NDC). 1 has three‐dimensional (3D) framework structure and exhibits strong luminescence in the solid state as well as in the suspended acetonitrile solution. Furthermore, it was found that the emission of 1 can be quenched efficiently by trace amounts of nitrofuran antibiotics (NFs) including nitrofurazone (NZF), furazolidone (FZD) and nitrofurantoin (NFT) with detection limits of 184, 243 and 263 ppb for NZF, FZD and NFT, respectively, even in the presence of other antibiotics such as penicillin (PCL).