Virtual trial assembly of a complex steel structure by Generalized Procrustes Analysis techniques

Robotic assembly of architectural structures has been an area of research for a few decades. Yet, current methods impose a large number of constraints on the geometry of those structures. In this paper we introduce a method for robotic assembly that enables the construction of double curved self-supporting structures. Latest research challenges have focused on the assembly of sophisticated brick structures and on sensor feedback systems for handling accuracy. We propose an alternative strategy to tackle tolerance handling in complex structures that rely on geometry. The intelligence of the system lies in two main aspects: a subdivision technique that incorporates the robot’s constraints as well as the structural equilibrium of the structure during each step of assembly, in order to omit the use of scaffolding; and a match between geometric information and the robot’s movements in a robot programming environment. As a proof of concept, we fabricated a portion of a full-scale double-curved structure. The structure was assembled without scaffolding by a portable KUKA KR10 on a randomly picked site. This project aims to demonstrate an easy and simple method for robotic assembly that enables the realization of digitally generated complex geometries as concrete complex structures.

Virtual assembly (VA) is a method to simulate the physical assembly (PA) of scanned parts. Small local part deviations can accumulate to large assembly deviations limiting the product quality. The propagation of geometrical deviations onto the assembly is a crucial step in tolerance management to assess the assembly quality. Current approaches for VA do not sufficiently consider the physical joining process. Therefore, the propagated assembly geometry may deviate strongly from the PA. In the state of the art, only specific and complex methods for particular joining processes are known. In this paper, the concept of Surrogate Models (SMs) is introduced, representing the connection between part and assembly geometries for particular joining processes. A Surrogate Modelling Toolbox (SMT) is developed that is intended to cover the variety of joining processes by the implementation of suitable SMs. A particular SM is created by the composition of suitable Surrogate Operations (SOs). An open list of SOs is presented. The composition of a SM is studied for a laser welding process of two polymer components. The resulting VA is compared to the PA in order to validate the developed model and is quantified by the exploitation ratio R.

PurposeThe purpose of this paper is to design a new method to realize automatic assembly of aircraft components with large shafts such as canard and vertical tail. The assembly structure of component with large shaft and fuselage is a mating assembly structure, and it is a challenge to satisfy the precision and assembly requirement.Design/methodology/approachAccording to the assembly structure features and process requirements of an aircraft component with large shaft, the operating principle of precise assembly system for shaft-hole mating is analyzed in this paper. The model of compliant assembly for shaft-hole mating is constructed, and force condition analysis of the compliant assembly is performed. An automatic precise shaft-hole assembly method for aircraft assembly using 5 degrees of freedom spatial mechanism, compliance technology and servo feeding system is put forward based on the analysis. A 5 degrees of freedom passive compliant experimental equipment has been developed.FindingsApplication test results of the 5 degrees of freedom passive compliant experimental equipment show that the simulated canard can be mated automatically and accurately through this method with high efficiency and high quality as long as the tip of shaft enters into the range of hole’s chamfer.Practical implicationsThis method has been used in an aircraft assembly project. The practical results show that the aircraft components with large shafts can be mated automatically and accurately through this method with high efficiency and high quality.Originality/valueThis paper presents a new method and designs a new assembly system to realize the assembly of the aircraft components with large shafts. The research will promote the automation of fuselage assembly.

: Free choice profiling (FCP) and generalized Procrustes analysis (GPA) were used to assess flavor differences in cooked bovine m. longissimus thoracis et lumborum (LTL) steaks sourced wholesale or from steers fed the same diet. Wholesale steaks were from LTL muscles that were either unaged or aged for 93 d with high or low visible marbling from old and young grass- and grain-finished cattle. The GPA of this sensory data showed that the 1st dimension contrasted grass- and grain-finished beef and accounted for 44.1% of the total variance, whereas the 2nd dimension contrasted unaged and aged beef and accounted for 22.9% of the variance. GPA was also used to assess flavor variation in cooked LTL steaks aged 4 or 14 d postmortem from 10 steers finished on the same diet, and the 1st 2 dimensions accounted for 39% of the total variance. Univariate analysis of beef aroma, flavor intensity, tenderness, and juiciness showed only tenderness increased with aging (P= 0.041) and Duncan's multiple comparison test on all FCP data indicated that aging beef up to 14 d shifted beef sensory characteristics toward increased tenderness, juiciness, and fatty flavor. The results of these studies showed that distinct flavors exist in beef from cattle finished in different production systems and that there is less variation in the flavor of beef from steers produced on the same farm than in beef available for general retail.

BackgroundThis study is aimed to (1) investigate the influence of sagittal and vertical patterns on mandibular cross-sectional morphology and to (2) provide visualized mandibular cross-sectional morphology in different groups with General Procrustes Analysis (GPA), canonical variance analysis (CVA) and discriminant function analysis (DFA).Methods324 cone-beam computed tomography (CBCT) images were collected to analyze mandibular cross-sectional morphology and were categorized into 12 groups according to sagittal and vertical pattern and gender. One-way analysis of variance (ANOVA) was used to compare the difference among the groups. Thirty equidistant points were marked along the contour of mandibular cross-section and GPA, CVA and DFA were applied.Results(1) Mandibular height in hyperdivergent groups was significantly higher than that in normodivergent and hypodivergent groups (P < 0.05). (2) Hypodivergent groups showed significantly wider upper third of mandibular width from symphysis to molar region than that in hyperdivergent group (P < 0.05), except for the premolar and molar regions in male groups (P > 0.05). (3) Class II hyperdivergent group showed narrowest lower third width in the molar region, with the mean value of 12.03 mm in females and 11.98 mm in males. (4) For males and females, the ratio between height and lower third width at symphysis was significantly higher in Class II hyperdivergent group than that in Class I hyperdivergent group (P < 0.05).Conclusions(1) The influence of vertical facial patterns on mandibular cross-sectional morphology is more obvious than that of sagittal skeletal pattern. (2) Subjects with increased vertical dimension presented with a remarkable “slimer” mandibular cross-sectional morphology at symphysis. (3) A deeper curve along the anterior contour of symphysis in Class II hyperdivergent group was noted with GPA.

ABSTRACTThe flavor of eight samples of commercial strawberry yogurt was studied by Free‐Choice Profile analysis (FCP). Generalized Procrustes Analysis (GPA) applied to FCP allowed differentiation between samples and highlighted flavor attributes responsible for the observed differences. The relation between sensory and physicochemical datasets was studied by means of GPA. Those samples with higher carbohydrate content were perceived as sweeter, having stronger strawberry flavor, and with more dairy and yogurt flavors. Samples with higher titratable acidity, ash and protein content were perceived as more acidic and higher in intensity of “faulty” or “defective” flavors. Higher moisture content was associated with lower intensity of “dairy” flavors (creamy, dairy, and yogurt) and greater intensity of rancid flavor. It is concluded that, though not often used to this end, GPA is a suitable method to study the relationship of sensory and instrumental measurements.

Virtual assembly was introduced in the chemical process simulation, and the method of virtual assembly for common chemical process was studied. The process of biomass fuel ethanol was analyzed which is combined by the first-grade distillation system in industrial ethanol production and the salt-added extractive distillation system in fuel ethanol production, and the scene graph structure was established. According to the assembly characteristics of the chemical process, the assembly equipment model was designed and constructed. The assembly points were added, and the assembly, simulation and transitive properties of the assembly points were defined. The 1+1and 1+n universality assembly method was proposed. By choosing unit equipment freely to assembly, the complex distillation system was realized. Results have shown that the assembly effect was good and accuracy, the method was proved correct and feasible. It is of great significance in the visual design of chemical process, digital construction of chemical plant and development of three-dimensional (3D) chemical process simulation technology.

BackgroundAdequate normalization minimizes the effects of systematic technical variations and is a prerequisite for getting meaningful biological changes. However, there is inconsistency about miRNA normalization performances and recommendations. Thus, we investigated the impact of seven different normalization methods (reference gene index, global geometric mean, quantile, invariant selection, loess, loessM, and generalized procrustes analysis) on intra- and inter-platform performance of two distinct and commonly used miRNA profiling platforms.Methodology/Principal FindingsWe included data from miRNA profiling analyses derived from a hybridization-based platform (Agilent Technologies) and an RT-qPCR platform (Applied Biosystems). Furthermore, we validated a subset of miRNAs by individual RT-qPCR assays. Our analyses incorporated data from the effect of differentiation and tumor necrosis factor alpha treatment on primary human skeletal muscle cells and a murine skeletal muscle cell line. Distinct normalization methods differed in their impact on (i) standard deviations, (ii) the area under the receiver operating characteristic (ROC) curve, (iii) the similarity of differential expression. Loess, loessM, and quantile analysis were most effective in minimizing standard deviations on the Agilent and TLDA platform. Moreover, loess, loessM, invariant selection and generalized procrustes analysis increased the area under the ROC curve, a measure for the statistical performance of a test. The Jaccard index revealed that inter-platform concordance of differential expression tended to be increased by loess, loessM, quantile, and GPA normalization of AGL and TLDA data as well as RGI normalization of TLDA data.Conclusions/SignificanceWe recommend the application of loess, or loessM, and GPA normalization for miRNA Agilent arrays and qPCR cards as these normalization approaches showed to (i) effectively reduce standard deviations, (ii) increase sensitivity and accuracy of differential miRNA expression detection as well as (iii) increase inter-platform concordance. Results showed the successful adoption of loessM and generalized procrustes analysis to one-color miRNA profiling experiments.

Abstract. The quality of individual ratings of conformation traits can commonly be evaluated by calculating inter-rater correlations and repeatability coefficients. We present an approach in which we associate the individual rating scores with the underlying horse shapes derived from standardized images, performing a shape regression. Therefore, we analyzed the shape of 102 Lipizzan stallions from the Spanish Riding School in Vienna, defined by 246 shape-correlated two-dimensional coordinates using techniques from the field of image analysis and geometric morphometrics. In addition we examined the differences in the conformation classifiers' perceptions of type traits and functional traits. In this study part, the rating scores of eight conformation classifiers were tested for agreement, yielding inter-rater correlations ranging from 0.30 to 0.55 and kappa coefficients ranging from 0.08 to 0.42. From the 12 scoring traits assessed on a valuating scale, type traits with a mean kappa coefficient (κ) of 0.27 demonstrated a higher agreement than functional traits (κ = 0.14). Based on 246 two-dimensional anatomical and somatometric landmarks, the shape variation was analyzed by the use of generalized orthogonal least-squares Procrustes (generalized Procrustes analysis – GPA) procedures. Shape variables were regressed into the results from visually scored linear type trait classifications (shape regressions). From the 48 performed shape regressions (eight classifiers, six traits), 42 % resulted in a significant equation. In 58 % of the ratings, no association between scores and the phenotype of the horses was found. Phenotypic differences of model horses along significant regression curves of mean ratings and individual ratings were exemplarily visualized and compared by warped and averaged images. Finally, we demonstrated that the method of shape regression offers the possibility to evaluate the association of individual ratings from expert conformation classifiers with the shapes of horses. The detected bias in classifiers' rankings have not been considered in breeding programs, and its impact on selection procedures still needs further research.

The influence of livestock production system [Freedom Extensive System (FES) versus Semi-Extensive System (SES)] and finishing feed (1.5 kg versus 3.0 kg of commercial feed in the finishing period) diet on sensory properties of foal meat using Generalized Procrustes Analysis (GPA) was studied. For this work, a total of 24 foals (8 from FES and 16 from SES) were used. Samples were evaluated by eight panelists for eight sensory attributes: colour, marbling, odour intensity, sweetness, springiness, hardness, chewiness, and juiciness. Data were analyzed using a GPA to minimize differences among testers. Highly appreciated sensory properties (odour intensity, red colour, marbling, and juiciness) were mostly associated with foals from the Semi-Extensive System. On the other hand, the three groups studied (FES, 1.5SES, and 3SES) were clearly recognized by panelists on the consensus configuration and they were clearly separated on the map. This study concluded that sensory characteristics of foal meat from a Semi-Extensive Production System with a finishing diet of 3 kg concentrate were more preferable than the other ones.

Characterization of the age-dependent shape of the pediatric thoracic spine and vertebrae using generalized procrustes analysis.

Perceptual mapping of citrus juices using projective mapping and profiling data from culinary professionals and consumers

The present study aims to assess the relationship between consumer perception and on-farm assessment of animal welfare performed using the Animal Needs Index 35L (ANI). Two tie-stall, 2 straw yard and 2 cubicle farms were scored by trained assessors using the ANI and filmed to produce six 3.5 min videos. Each of them contained 4 clips: barn overall view, feeding, milking and individual animals. Ten untrained observers were asked to elicit terms describing how they perceived the observed farming systems to affect animal welfare using Free Choice Profiling (FCP). Data from FCP were subjected to Generalised Procrustes Analysis (GPA). GPA showed a significant consensus among observers. Observers characterised the first dimension with terms ranging from constrictive to comfortable conditions and the second one in terms of cleanliness/dirtiness. Principal Component Analysis (PCA) was conducted using the scores of the farms on the first two dimensions of GPA and the data gathered through the ANI. The first dimension of GPA (Comfortable), ANI's sheet 1 (Locomotion), sheet 2 (Social interaction) and sheet 6 (Total score) showed high loadings on the first component of PCA, whereas the second dimension of GPA (Clean), sheet 3 (Flooring) and sheet 4 (Stockmanship) were correlated with the second component of PCA. We concluded that FCP may be used to elicit lay person perception of welfare-related characteristics of dairy cattle farming systems, thus providing a tool to study the relationships between consumer perception and on-farm assessment of animal welfare.

Thirty-nine port wines with a range of different colors, including four of known ages were profiled in duplicate for nine attributes of appearance by a panel of seven tasters. Each assessor developed his own set of terms to describe the samples. A generalized Procrustes analysis (GPA) was carried out on this profile data and a consensus space obtained. The first two axes of the consensus space accounted for 85.3% and 6.6% of the variation, respectively. Spectrophotometric measurements related to color were also done on the same sample set, and these data were analyzed using principal component analysis (PCA). Regression of the scores on the first principal axis of the GPA consensus and those from the PCA of the color measurements showed a very strong relationship. Quality ratings obtained in independent tasting sessions were also regressed on the scores from the GPA and PCA axes, and it was shown that the lighter and browner ports were associated with higher quality ratings.

Virtual trial assembly of large steel members with bolted connections based on point cloud data