Hidden Defect Research Articles

An Optimal Opportunistic Maintenance Planning Integrating Discrete- and Continuous-State Information

Information-driven group maintenance is crucial to enhance the operational availability and profitability of diverse industrial systems. Existing group maintenance models have primarily concentrated on a single health criterion upon maintenance implementation, where the fusion of multiple health criteria is rarely reported. However, this is not aligned with actual maintenance planning of multi-component systems on many occasions, where multi-source health information can be integrated to support robust decision making. Additionally, how to improve maintenance effectiveness through a scientific union of both scheduled and unscheduled maintenance remains a challenge in group maintenance. This study addresses these research gaps by devising an innovative multiple-information-driven group replacement policy for serial systems. In contrast to existing studies, both discrete-state information (hidden defect) and continuous degradation information are employed for group maintenance planning, and scheduled postponed maintenance and unscheduled opportunistic maintenance are dynamically integrated for the first time to mitigate downtime loss. To be specific, inspections are equally spaced to reveal system health states, followed by the multi-level replacement implemented when either (a) the degradation of the continuously degrading unit reaches a specified threshold, or (b) the age of the multi-state unit since the defect’s identification reaches a pre-set age (delayed replacement). Such scheduling further enables the implementation of multi-source opportunistic replacement to alleviate downtime. The Semi-Markov Decision Process (SMDP) is utilized for the collaborative optimization of continuous- and discrete-state thresholds, so as to minimize the operational costs. Numerical experiments conducted on the critical structure of circulating pumps verify the model’s applicability.

Mechanism of Detecting the Construction Quality of a Diaphragm Wall by an Infrared Thermal Field and Engineering Application.

During underground space exploitation in the urbanization process, numerous foundation pits were constructed where a diaphragm wall was often used as a retaining structure and waterproof curtain. Due to complicated engineering geological conditions or improper construction, diaphragm walls and wall joints often exhibit quality defects. Groundwater leaked from these quality defects to foundation pits during excavation, endangering the safety of the pit and surrounding facilities. The current leakage identification of the underground retaining structure was performed by artificial visual detection, which cannot satisfy the engineering requirement. The temperature field in the leakage area of the diaphragm wall was different from other areas. The leakage wall imaging system using a thermal imager was efficient in visualizing leaking, which was not visible to the naked eye. In this study, infrared thermal imaging technology was introduced in potential leakage detection for the diaphragm wall of a foundation pit. The infrared radiation characteristics of the diaphragm wall leakage and the potential leakage parts were studied through laboratory simulation tests and on-site detection methods. The maximum temperature appeared at the water outlet and the surface of the defect with hidden defect, and the temperature field was symmetrically distributed along the cross-section direction. In the potential leakage area, the temperature difference at the penetration point was 23.4 °C when the initial water pressure was 10 kPa. The temperature difference at the penetration point was 21.8 °C when the initial water pressure was 30 kPa. In the field test, the maximum temperature difference between the leakage area and the surrounding wall was 4.5 °C. The study can provide a reference for similar engineering.

TANGGUNG JAWAB DEALER TERHADAP INDENTOR DALAM PERJANJIAN JUAL BELI MOBIL DENGAN SISTEM INDEN

In this journal, the author discusses the issue of dealer responsibility for indentor in car buying and selling agreements with indent systems. The purpose of writing this journal is to find out the implementation of the sale and purchase agreement with the indent system at PT. Hadji Kalla Toyota Baubau in addition to knowing how the dealer's responsibility if the car received indentor is not in accordance with the promised. This research is an empirical legal paper and uses a qualitative approach with primary data sources obtained from interview results and secondary data obtained from the literature study process. 
 The data analysis method used in this study is qualitative descriptive. The results showed that in the implementation of buying and selling consumers were given an order form in the form of Vehicle Order Letters and paid a finished mark of Rp. 5,000,000-, for a cash-indented car advance of at least 30% while the credit indent was at least 25% of the price of the car ordered. 
 The dealer's responsibility when default is if the car received late the dealer always provides the latest information about delivery, If there is a hidden defect in the dealer's car replaces the damage with factory standards, if the car received does not match the color ordered the dealer offers the car with the same type of different color. PT. Hadji Kalla Toyota Baubau should write clearly in the Vehicle Order Letter important points such as certainty of delivery time, vehicle repayment deadline, and risk of violation of these points and provide assurance to consumers in purchase in indent by maintaining communication between the dealer and the manufacturer to reduce the risk of delays and errors in delivery and the quality of goods (no damage) of the vehicle.

Debonding defect quantification method of building decoration layers via UAV-thermography and deep learning

The falling offs of building decorative layers (BDLs) on exterior walls are quite common, especially in Asia, which presents great concerns to human safety and properties. Presently, there is no effective technique to detect the debonding of the exterior finish because debonding are hidden defect. In this study, the debonding defect identification method of building decoration layers via UAV-thermography and deep learning is proposed. Firstly, the temperature field characteristics of debonding defects are tested and analyzed, showing that it is feasible to identify the debonding of BDLs based on UAV. Then, a debonding defect recognition and quantification method combining CenterNet (Point Network) and fuzzy clustering is proposed. Further, the actual area of debonding defect is quantified through the optical imaging principle using the real-time measured distance. Finally, a case study of the old teaching-building inspection is carried out to demonstrate the effectiveness of the proposed method, showing that the proposed model performs well with an accuracy above 90%, which is valuable to the society.

مرورالزمن المانع في دعوى ضمان العيوب الخفية "عقد البيع أنموذجاً" دراسة مقارنة بين أحكام الفقه الإسلامي وأحكام القانون المدني الأردني

تناولت هذه الدراسة مرور الزمن المانع من سماع الدعوى في دعوى ضمان العيوب الخفية، كدراسة مقارنة بين أحكام الفقه الإسلامي وأحكام القانون المدني الأردني، حيث تم تقسيم هذه الدراسة إلى مبحثين، خصص الأول للحديث عن مفهوم ضمان العيب الخفي وشروط تحققه حيث تم تقسيم هذا المبحث إلى مطلبين الأول منه تناول مفهوم الضمان والعيب لغة واصطلاحاً أما الثاني فقد خصص للحديث عن شروط العيب الموجب للضمان حيث تناولنا الشروط المتعلقة بماهية العيب نفسه والشروط التي لا تتعلق بماهية العيب. أما المبحث الثاني فقد خصص للحديث عن أثر مرور الزمن المانع في دعوى ضمان العيوب الخفية حيث تم تقسيم هذا المبحث إلى مطلبين خصص الأول للحديث عن ماهية الدفع بعدم سماع الدعوى لمرور الزمن عليها، أما الثاني فقد خصص للحديث عن الشروط الواجب توافرها لصحة الدفع بمرور الزمن في دعوى ضمان العيوب الخفية.

On the hidden defect behind the proof of the important theorem lim(x→0)sin⁡x/x=1 in calculus

On the hidden defect behind the proof of the important theorem lim(x→0)sin⁡x/x=1 in calculus

Ultrasonic Bulk Waves Measurements for Defect Detection of Composite Materials

The defect detection in composite material is important for its quality control where the hidden defect such as crack, corrosion, notch, holes, void and porosity can develop. In this paper, the ultrasonic bulk wave measurements of longitudinal and shear waves are used to identify defect in the multilayered composite material. This study employs pulse echo technique and utilized angle beam transducer. The composite material model investigated in this contribution are made of 24 mm and 12 mm thick Aluminium plates with a width of 100 mm and a length of 203 mm which are separated with an approximately 1 mm thick oil layer. A simulated defect is created in the composite test material by drilling a hole with 2.5 mm diameter and 3 mm depth on the bottom surface of the third layer material. Finding indicates that the defect is located at 53.39 mm from transducer and the percentage difference of the defect location compared to the calculation method is 7%. It indicates that the proposed method can be use to detect defect in multilayered composite material within 10% accuracy compared to the calculation method.

Perspectives of Straw-Bale Building as Environmentally Safe Construction

There was presented urgency of ecological construction. There was offered the concept of eco house. As a natural building material for eco house was offered straw. There was described its construction, sound and heat insulating properties, that entirely satisfied construction standards. There were revealed undeniable advantages of straw as an ideal building material in comparison with known natural materials. There were explored explicit and hidden defect of straw for the building of eco houses. There were considered ways of elimination of existing lacks and features of straw as ecological building material. There were given the recommendations for technology enhancement for straw-bale building. There was drawing a conclusion about the prospects of straw-bale building and the need to develop standard designs and designer solutions for Russia.

Hidden defect recognition based on the improved ensemble empirical decomposition method and pulsed eddy current testing

This article presents a new approach for recognizing hidden defects in conductive structures based on the improved ensemble empirical decomposition (IEEMD) and the pulsed eddy current (PEC) testing technique. First, the ensemble empirical mode decomposition (EEMD) method is improved in terms of envelope fitting, end effects and false components. Then, feature vector composed of the principal marginal spectrum peaks are extracted by the help of Hilbert weighted frequencies and characteristic frequencies. It has been verified by simulation signals that the IEEMD method can obtain more accurate intrinsic mode function components (IMFs). The proposed feature extraction method may recognize various hidden defect in the rail specimen with satisfying accuracy and robustness to such disturbances as noise and liftoff.

Induction thermography: principle, applications and first steps towards standardisation

A survey on theory, characteristic quantities and the experimental technique of induction thermography is given. Induction thermography is used for surface defect detection in forged parts of ferromagnetic steel at typical frequencies of 100–300 kHz. The sensitivity for crack detection is comparable to magnetic particle inspection. A hidden defect in ferritic steel with a coverage of 140 μm was detected by lowering the induction frequency down to 1500 Hz. Defects of fibres were detected in carbon fibre reinforced polymer (CFRP). Inductive excitation is complementary to flash excitation. By increasing the induction frequency up to 52 MHz, surface heating of CFRP can be realised. Cracks in silicon solar cells were detected. The crack tip is revealed with very high contrast. A new field is crack detection in railway components like rails and wheels. In rails, a larger defect could be detected from a test car moving at a speed of up to 15 km/h. A fully automated wheel testing system was built up as a demonstrator, that can detect defects with comparable sensitivity to magnetic particle testing. Standardisation of thermography has gained progress in the last years and will lead to standards on active thermography, flash excited and induction thermography in the next future.

Подготовка бакалавров-психологов: неопределенность целеполагания, риски и возможности их преодоления

The paper analyzes the uncertainty of goal-setting in the preparation of bachelors in Psychology to social work; the structure of competences, the final examination criteria for graduates. We describe the risks in training programs in the selection of the content and teaching technologies: lack of the principles of academic and applied bachelor content distinction; risk of a “clip” format of teaching students due to the shortage of time for the acquisition of the academic disciplines content; the risk of "hidden defect" in the development of professionally important qualities in graduates. We outline the methodology to overcome these risks: the implementation of the principle of the unity of the "philosophy of practice" and the science of psychology; the standard of the psychologist work should be the basis of the content selection and didactic training of psychologists; the principle of integration of the human sciences is a functional element of the social system, free and sovereign personality, and individual organism.

A Novel Non-Destructive Evaluation (NDE) Technique Using Coplanar Capacitive Imaging Probes

Abstract A novel NDE technique, known as capacitive imaging (CI), is introduced in this work. The CI approach uses a coplanar probe with two or more electrodes in air to produce a quasi-static electric field distribution within the material. The capacitive coupling allows this technique to detect both surface and hidden defect in insulating materials, and provide indications of surface profile of conducting materials. Scanning the electrodes over the material can form an image according to the changes in the output voltage from the coplanar CI probe. In this work, a detailed description of the CI technique is presented, including the theory, modes of operation, instrumentation, and some preliminary experimental results.

On the small-defect perturbation and sampling of heterogeneous solids

This paper aims to extend the application of topological sensitivity, developed for elastic-wave imaging of defects in a homogeneous background medium, to the class of heterogeneous (background) bodies with piecewise-analytic viscoelastic and mass density coefficients. Founded on the premise of time-harmonic wave propagation, the approach employs dimensional analysis to formally establish the expected, yet previously unavailable result wherein the leading behavior of the scattered field caused by a vanishing inclusion is governed by (1) the illuminating visco-elastodynamic field and its adjoint companion, both computed for the background body, at the sampling point; (2) the geometry and material properties of the vanishing defect, and (3) local properties of the (heterogeneous) background solid at the sampling point. By virtue of this result, an explicit formula for the topological sensitivity is obtained by an asymptotic expansion of a misfit-type cost functional with respect to the nucleation of a trial inclusion in the given background, i.e. reference solid. Through numerical examples, it is shown that such defined sensitivity provides a computationally effective platform for preliminary sounding of heterogeneous solids by viscoelastic waves. This is accomplished by computing the topological sensitivity over an arbitrary grid of sampling points inside the reference solid, and identifying those regions where the topological sensitivity attains pronounced negative values with the support of a hidden defect (or a set thereof). The results further highlight the potential of topological sensitivity to expose not only the geometry, but also the nature of internal defects through a local, point-wise identification of “optimal” inclusion properties that minimize the topological sensitivity at a given sampling location.

FOLD HELICAL PROTEINS BY ENERGY MINIMIZATION IN DIHEDRAL SPACE AND A DFIRE-BASED STATISTICAL ENERGY FUNCTION

Statistical energy functions are discrete (or stepwise) energy functions that lack van der Waals repulsion. As a result, they are often applied directly to a given structure (native or decoy) without further energy minimization being performed to the structure. However, the full benefit (or hidden defect) of an energy function cannot be revealed without energy minimization. This paper tests a recently developed, all-atom statistical energy function by energy minimization with a fixed secondary helical structure in dihedral space. This is accomplished by combining the statistical energy function based on a distance-scaled finite ideal-gas reference (DFIRE) state with a simple repulsive interaction and an improper torsion energy function. The energy function was used to minimize 2000 random initial structures of 41 small and medium-sized helical proteins in a dihedral space with a fixed helical region. Results indicate that near-native structures for most studied proteins can be obtained by minimization alone. The average minimum root-mean-squared distance (rmsd) from the native structure for all 41 proteins is 4.1 A. The energy function (together with a simple clustering of similar structures) also makes a reasonable selection of near-native structures from minimized structures. The average rmsd value and the average rank for the best structure in the top five is 6.8 A and 2.4, respectively. The accuracy of the structures sampled and the structure selections can be improved significantly with the removal of flexible terminal regions in rmsd calculations and in minimization and with the increase in the number of minimizations. The minimized structures form an excellent decoy set for testing other energy functions because most structures are well-packed with minimum hard-core overlaps with correct hydrophobic/hydrophilic partitioning. They are available online at http://theory.med.buffalo.edu.

On Vivacity: The Difference between Daydreaming and Imagining-Under-Authorial-Instruction

WHEN WE SPEAK IN EVERYDAY conversation about imagination, we often attribute to it powers that are greater than ordinary sensation. But when we are asked to perform concrete experiment of comparing an imagined object with a perceptual one-that is, of actually stopping, closing our eyes, concentrating on imagined face or imagined room, then opening our eyes and comparing its attributes to whatever greets us when we return to sensory world-we at once reach opposite conclusion: imagined object lacks vitality and vivacity of perceived; it is in fact these very attributes of vitality and vivacity that enable us to differentiate actual world present to our senses from one that we introduce through exercise of imagination. Even if, as Jean-Paul Sartre observes, object we select to in this experiment is face of a beloved friend, one we know in intricate detail (as Sartre knew faces of Annie and Pierre), it will be, by comparison with an actually present face, thin, dry, two-dimensional, and 'inert.' It seems that we tend to notice this phenomenon only when we are especially keen on seeing a face, only when we desperately care to have it present in mind with clarity and force. We then notice deficiency and, like Proust's Marcel, who berates himself for his inability to picture face of Albertine or face of his grandmother, we conclude that vacuity of our imagining is somehow peculiar to our feeling about this particular person and that there must be a hidden defect in our affection. In fact vacuity is general, and all that is peculiar or particular to such cases is intensity of wishing to imagine that makes us confront, with more than usual honesty, fact that we cannot do so. It is when we are soaked with longing to that we notice, as John Keats confessed, the fancy cannot cheat so well/As she is fam'd to do.2 By means of vividness of perceptions, we remain at all moments capable of recovering, of recognizing material world and distinguishing it from our imaginary world, even as we lapse into and out of our gray and ghostly daydreams. Aristotle refers to this grayness as the feebleness of images. Sartre calls it their essential poverty. Of course, insofar as imagination is enfeebled and impoverished, it is so only on sensory grounds. To complain that imagined object lacks vivacity and

STUDIES IN FOREST PATHOLOGY: XII. DECAY OF WESTERN HEMLOCK IN THE UPPER COLUMBIA REGION, BRITISH COLUMBIA

An investigation of western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the Upper Columbia region has shown that decay losses are excessive, amounting to 52 and 74% in terms of cubic and board foot computations respectively. The logs of 833 hemlock on 36 sample plots located in mature timber were analyzed in detail. Twenty-six decay-producing fungi have been isolated. Sixty-two per cent of the total decay was attributed to Echinodontium tinctorium Ell. & Ever. and 25% to Fomes pini (Thore) Lloyd. Considerable variation in the fungi responsible for decay was encountered intraregionally. Stand defect losses varied from 38 to 71%. Some of this variation could be predicted on the basis of the site index determinations of hemlock. Relative to the total incidence and importance of decay, Echinodontium tinctorium decreased and Fomes pini increased in significance with increasing site quality. Sporophores, scars, dead tops, large rotten branches, swollen knots, frost cracks, forked trees, and trunk infections of mistletoe were classed as indicators of significance in relation to hidden defect. Living trees, classed as Suspect or Residual depending on the presence or absence of one or more reliable indicators of defect, were found to differ appreciably in average defect. Within each of the preceding classes decay increased progressively with increasing diameter and decreasing site quality. Immature hemlock was found to be susceptible to appreciable decay and mature stands reached an advanced stage of deterioration at 250 years. Multiple correlation analyses between percentage of decay, site, age, and the relative percentage of Residual trees weighted by volume permitted an estimate of total stand defect within ± 7%.

Negligence. Hidden Defect

Negligence. Hidden Defect