Repeat Inspection Research Articles

Evaluation of Different Control Strategies for Trajectory Following of a Robotic Capsule Endoscope Under Rotating Magnetic Actuation

Current wireless capsule endoscopy (WCE) is limited in the long examination time and low flexibility since the capsule is passively moved by the natural peristalsis. Efforts have been made to facilitate active locomotion of WCE using magnetic actuation and localization technologies. In this work, we investigate the trajectory following problem of a robotic capsule under rotating magnetic actuation, in order to realize efficient and accurate navigation of the capsule in the narrow, complex intestinal environments. Specifically, four control strategies are developed based on the PD controller, adaptive controller (AC), model predictive controller (MPC) and robust multi-stage model predictive controller (RMMPC). In particular, the RMMPC method takes into account the uncertainty in the intestinal environment by modeling the intestinal peristalsis and friction in the controller design. We evaluate the proposed methods in simulation as well as in real-world experiments in several tubular environments, including plastic phantoms with complex shapes and an ex-vivo pig colon. The results have demonstrated the potential of the proposed control methods to realize accurate and efficient inspection of the intestine using active WCE. Our methods can be integrated with current WCE to improve the diagnostic accuracy and efficiency of the GI tract. <i>Note to Practitioners</i>&#x2014;The motivation of this paper is to solve the trajectory following problem for active WCE in the human intestine to realize accurate, efficient and repeatable inspection of the gastrointestinal (GI) tract. We present four different control strategies for 5-DOF control of a robotic capsule endoscope actuated by a reciprocally rotating permanent magnet to make the capsule follow a predefined trajectory in a tubular environment. The accuracy and efficiency of the approach are validated in simulation and real-world experiments. The proposed trajectory following strategies can be integrated into existing WCE products to allow automatic and repeatable examination of the GI tract, and can also be extended to the locomotion of other tethered or untethered magnetic devices in the tubular environments for different medical and industrial applications. In the future, our proposed approach is expected to be combined with image-based automatic diagnosis of the GI tract to provide doctors with better tools for digestive examinations.

Predicting Food Safety Compliance for Informed Food Outlet Inspections: A Machine Learning Approach.

Consumer food environments have transformed dramatically in the last decade. Food outlet prevalence has increased, and people are eating food outside the home more than ever before. Despite these developments, national spending on food control has reduced. The National Audit Office report that only 14% of local authorities are up to date with food business inspections, exposing consumers to unknown levels of risk. Given the scarcity of local authority resources, this paper presents a data-driven approach to predict compliance for newly opened businesses and those awaiting repeat inspections. This work capitalizes on the theory that food outlet compliance is a function of its geographic context, namely the characteristics of the neighborhood within which it sits. We explore the utility of three machine learning approaches to predict non-compliant food outlets in England and Wales using openly accessible socio-demographic, business type, and urbanness features at the output area level. We find that the synthetic minority oversampling technique alongside a random forest algorithm with a 1:1 sampling strategy provides the best predictive power. Our final model retrieves and identifies 84% of total non-compliant outlets in a test set of 92,595 (sensitivity = 0.843, specificity = 0.745, precision = 0.274). The originality of this work lies in its unique and methodological approach which combines the use of machine learning with fine-grained neighborhood data to make robust predictions of compliance.

Data-Driven Railway Crosstie Support Condition Prediction Using Deep Residual Neural Network: Algorithm and Application

Ballasted track substructure is designed and constructed to provide uniform crosstie support and serve the functions of drainage and load distribution over trackbed. Poor and nonuniform support conditions can cause excessive crosstie vibration which will negatively affect the crosstie flexural bending behavior. Furthermore, ballast–tie gaps and large contact forces at the crosstie–ballast interface will result in accelerated ballast layer degradation and settlement accumulation. Inspection of crosstie support condition is therefore necessary while very challenging to implement using current methods and technologies. Based on deep learning artificial intelligence techniques and a developed residual neural network (ResNet), this paper introduces an innovative data-driven prediction approach for crosstie support conditions as demonstrated from a full-scale ballasted track laboratory experiment. The discrete element method (DEM) is leveraged to provide training and testing data sets for the proposed prediction model. K-means clustering is applied to establish ballast layer subsections with representative ballast particles and provide additional insights on layer zoning for dynamic behavior trends. When provided with DEM simulated particle vertical accelerations, the proposed deep learning ResNet could achieve 100% training and 95.8% testing accuracy. Fed with vertical acceleration measurements captured by advanced “SmartRock” sensors from a full-scale ballasted track laboratory experiment, the trained model could successfully reach a high accuracy of 92.0%. Based on the developed deep learning approach and the research findings presented in this paper, the innovative crosstie support condition prediction system is envisioned to provide railroaders accurate, timely, and repeatable inspection and monitoring opportunities without disrupting railway network operations.

Design for automated inspection in remanufacturing: A discrete event simulation for process improvement

Remanufacturing is a process of restoring end-of-life (Eol) products to “as new” condition with a matching warranty. It offers significant economic benefits to remanufacturers as well as providing enormous environmental and social benefits. However, achieving remanufacturing is complex and uncertain due to varying product return quantity and quality. These uncertainties call for proper assessment of returned Eol products to extract the most value from them. The evaluation involves inspecting the Eol products on arrival for remanufacturing, thereby making the most appropriate Eol decisions. These decisions are made by expert personnel by visually assess these products manually or using semi-automated techniques. However, the accuracy of these decisions is subjective, time-consuming, and prone to missing defects. The need to develop processes and tools for efficient, reliable, and repeatable inspection in remanufacturing becomes inevitable. Automated inspection becomes handy to improve the assessment of these defects as well as saving time. This paper proposes design-for-inspection as a tool to enhance remanufacturing. A discrete event simulation of this model for the torque converter remanufacturing process is presented and highlights the benefits of automating the remanufacturing inspection process. It further suggests the design improvements to obtain an enhanced automated inspection.

High-temperature in-process inspection followed by 96-h robotic inspection of intentionally manufactured hydrogen crack in multi-pass robotic welding

This investigation introduces two new techniques to quantitatively address the challenging problem of understanding Hydrogen Induced Cracking (HIC) in welding processes. The first technique is a novel procedure to create a known and controlled HIC in a welded sample. The second is an in-process monitoring technique to measure the initial formation and subsequent growth of the HIC in a multi-pass weld whilst being compatible with the high temperatures associated with the welding process. The HIC was initiated using a localised quenching method of the weld and its character was verified using both macrograph and microscopic investigations. During HIC initiation and growth, the sample was monitored every 1–30 min for a total of 96 h using a custom non-destructive testing (NDT) system, mounted on a robot which ensured repeatable inspection positioning. Combining these techniques has therefore allowed for the first time, a detailed understanding of the evolution of HIC in a multi-pass welded sample. Our findings reveal that the HIC was initiated 43 min after the weld ended and that it then grew rapidly for about 15 min and continued growing at a slower rate for around 24 h. No significant growth was observed for the remaining 72 h of the experimental measurement.

Modified Reliability Centered Maintenance Analysis Considering Probability of Detection

In the maintenance of aircraft structural parts, a routine inspection is conducted to prevent fatigue crack growth beyond the critical size during the service life. Traditionally, the inspection interval is determined by a reliability centered maintenance analysis (RCMA), which accounts for the stochastic nature of crack growth. In a practical nondestructive inspection (NDI), however, the probability of detection curve should be considered as well to reflect the detectability during the inspection. In this paper, a new RCMA is proposed that incorporates this. Despite the modern simulation approaches available in recent years, the highlight of the method is that all the equations are developed in an analytical way, which may be more useful in the real field of maintenance. Two examples are given to illustrate the applications: one is to determine the repeat inspection interval under the four POD curves in the NDI; and the other is to determine the maximum operation time until the next inspection, when an aircraft had an earlier inspection packaged with others. As a result, more appropriate inspection plans are obtained than the existing RCMA in terms of reliability and availability.

Colorectal cancer prevention by a CLEAR principles–based colonoscopy protocol: an observational study

Colorectal cancer (CRC) prevention by colonoscopy has been lower than expected. We studied CRC prevention outcomes of a colonoscopy protocol based on Clean the colon, Look Everywhere, and complete Abnormality Removal (CLEAR) principles. This observational follow-up study studied patients provided screening colonoscopy at a free-standing private ambulatory surgery center in South Carolina by 80 endoscopists from October 2001 to December 2014, followed through December 2015. The colonoscopy protocol, optimized for polyp clearance, featured in-person bowel preparation instructions reinforced by phone, polyp search and removal throughout insertion and gradual withdrawal with circumferential tip movements, and a team approach using all personnel present to maximize polyp detection, patient safety, and clear-margin polypectomy including requesting repeat inspection or additional tissue removal. Outcome measures were postscreening lifetime CRC risk relative to Surveillance Epidemiology and End Results (SEER)-18 and interval cancer rate (postcolonoscopy CRCs among cancer-free patients at screening). Of 25,862 patients (mean age, 58.1 years; 52% black; 205,522 person-years of observation), 159 had CRC at screening and 67 patients developed interval CRC. The interval CRC rate was 3.34 per 10,000 person-years of observation, 5.79 and 2.24 among patients with and without adenomas, respectively. The rate was similar among older patients (mean age 68.5 years at screening) and with prolonged follow-up. Postscreening lifetime CRC risk was 1.6% (bootstrap 95% confidence interval, 1.3%-1.8%) versus 4.7% in SEER-18, 67% lower. Subgroups with mean screening ages of 50 and 68.5 years showed risk reductions of 80% and 72%, respectively. The adverse event rate was less than usually reported rates: perforation 2.6 per 10,000, bleeding with hospitalization 2.4 per 10,000, and no deaths. A colonoscopy protocol optimized for polyp clearance prevented 67% of CRC compared with a SEER-18 population given ongoing population screening.

The Effectiveness of Laser Shearography for the Inspection of Wall Thinning in a Large Aluminum Plate

Laser shearography is a powerful optical tool that is able to directly measure the displacement derivatives using interferometric effects. Stroboscopic shearography provides a full field, reliable and repeatable inspection process that facilitates defect visualization. The aim of this paper is to investigate the effectiveness of laser shearography for inspection of a large aluminum plate with a large wall thinning. A modified Michelson interferometer is introduced in order to inspect the entire aluminum plate simultaneously. The wall thinning is visualized as the region of the anomaly in the quasi-uniform and homologous shearography fringe pattern. The boundaries of the wall thinning cannot be indicated precisely due to the nature of the formation of shearography fringes. Therefore, the small shearing method is applied to determine the dimensions of the wall thinning. This approach allows for the detection of the wall thinning in the wider range of excitation frequencies. The wall thinning is successfully detected using the small shearing method as a light rectangle in the inconspicuous background. Finally, a novel averaging approach is proposed to eliminate the effects of noise and uncertainty in the calculation of the boundaries. Using this approach, the shearography interferometric effects are significantly reduced.

Development of PZT-excited stroboscopic shearography for full-field nondestructive evaluation.

Nondestructive evaluation using shearography requires a way to stress the inspection target. This technique is able to directly measure the displacement gradient distribution on the object surface. Shearography visualizes the internal structural damages as the anomalous pattern in the shearograpic fringe pattern. A piezoelectric (PZT) excitation system is able to generate loadings in the vibrational, acoustic, and ultrasonic regimes. In this paper, we propose a PZT-excited stroboscopic shearography. The PZT excitation could generate vibrational loading, a stationary wavefield, and a nonstationary propagation wave to fulfill the external loading requirement of shearography. The sweeping of the PZT excitation frequency, the formation of a standing wave, and a small shearing to suppress the incident wave were powerful controllable tools to detect the defects. The sweeping of the PZT excitation frequency enabled us to determine one of the defect-sensitive frequencies almost in real time. In addition, because the defect sensitive frequencies always existed in wide and plural ranges, the risk of the defect being overlooked by the inspector could be alleviated. The results of evaluation using stroboscopic shearography showed that an artificial 20 mm-diameter defect could be visualized at the excitation frequencies of 5-8 kHz range and 12.5-15.5 kHz range. This technique provided full field reliable and repeatable inspection results. Additionally, the proposed method overcame the important drawback of the time-averaged shearography, being required to identify the resonance vibration frequency sensitive to the defect.

Demonstrating good practice in the safe operation of gas assets with predictive analytics

The oil and gas industry operates large and complex facilities. Technical integrity (and thus licence to operate) must be maintained through routine inspection and maintenance regimes. Corrosion attacks every component at every stage in the life of every oil and gas field or plant (Schlumberger 1994). Globally, corrosion management accounts for US2.5Tr cross-industry spend (NACE International 2016). Risk-based approaches for internal corrosion based on susceptibility of a process item to corrode, have been utilised to assist with identifying appropriate and more cost-effective maintenance and inspection strategies. The aim of such approaches is to protect integrity and not compromise safety; however, they do nothing to minimise regret cost. These approaches use only known physical characteristics of piping equipment and rely on repeat inspection data to calculate corrosion rates and associated maintenance schedules. The present paper will leverage the challenges and shortcomings of using existing risk-based inspection (RBI) approaches and demonstrate how Accenture in collaboration with Woodside and others is utilising predictive analytics to more accurately determine likelihood of corrosion to exist in a more granular resolution, thus managing likelihood and consequence of corrosion to produce an improved risk-based model. The analytics model considers physical, geospatial and external factors for external corrosion. This is a work in progress, with very promising initial results, that leads into the implementation of an improved RBI strategy, enabling Woodside to reduce inspection scope, physical site activity and associated management cost. In addition, it better manages plant risk in conjunction with smart visualisation tools.

American Christians and the Emptiness of Death

My office is the antithesis of emptiness. I am not sure how many books I have managed to cram into a 9 by 12 room, but suffice it to say I have used every available space, even to the point of violating the university's fire code. A year ago, when the fire marshal came around for a routine inspection, he informed me that I could not stack books all the way to the ceiling on top of 6-foot bookshelves but had to leave at least 12 inches' clearance. He told me he would be back for a repeat inspection in a couple of months. This forced me to do some culling—an excruciating task. So over spring break, I reluctantly downsized. Though every book now stood properly upright on a shelf, there was not an inch left anywhere in which to fit even one more volume.

Numerical Estimation of Flight Cycle and Repeat Inspection Interval

In the present paper, an aircraft control surface flight cycle is predicted considering corner flaws and through crack under transport wing standard load using the NASGRO model available in AFGROW software. The effect of corner flaws length, depth of countersunk, panel thickness, axial load to pin load, composite patch, and disbond factor on the normalized stress intensity factor, critical flight cycle, and repeat inspection interval are investigated. The typical numerical prediction of the critical flight cycle is validated with analytical estimation and published experimental results, and shows excellent agreement.

A Nonpolynomial Optimal Algorithm for Sequencing Inspectors in a Repeat Inspection System with Rework

Assuming that two types of inspection errors are nonidentical and that only the items rejected by an inspector are reworked and sent to the next inspection cycle, we formulate a combinatorial optimization problem for simultaneously determining both the minimum frequency of inspection-rework cycles and the optimal sequence of inspectors selected from a set of available inspectors, in order to meet the constraints of the outgoing quality level. Based on the inherent properties from our mathematical model, we provide a nonpolynomial optimal algorithm with a time complexity ofO(2m).

Data conflicts: the dwindling power of a study.

I have read the article “Consequences of spilled gallstones during laparoscopic cholecystectomy (LC)” by Suvi Virupaksha [1] with interest. The unpredictable outcome of spilled gallstones that are left un-retrieved during LC is often a cause of future embarrassment for the operating surgeon. So, it comes as a surprise that most instances of unrecovered spilled gallstones are neither documented in the operation notes nor disclosed to the patients. This prospective observational study was carried out in 150 (1 gallbladder polyp, 2 acalculous cholecystitis, and 147 gallstones) patients of LC over a period of one year. There are many glaring inconsistencies in the presented data that merit clarification by the author. The table outlining the ultrasound findings mentioned of 10 patients with solitary gallstone while multiple stones were detected in 135 patients. This amounts to a total of 145 instead of 147 patients with gallstone disease. Similarly, the sum total of patients of the three different groups categorized on the basis of stone size is 156 instead of 147. The author has variably reported the incidence of gallstone spillage in this article (19.04 % in the text and 18.91 % in the table). All the instances of gallstone spillage in this series were secondary to gallbladder perforations, but in the table comparing the results of the present study with international data, the reported incidence of spillage is more than that of gallbladder perforation. The various mechanisms responsible for gallbladder perforation are detailed in a tabular form; however, the numbers mentioned against different mechanisms are quite confusing as they are neither adding up to the total number of patients nor to the percentage of patients with spilled stones. The author has boasted of zero percent incidence of un-retrieved gallstones, but at the same time, mentioned of a patient with port-site wound complication secondary to a left out gallstone in the subcutaneous plane. The author could have analyzed the incidence of spilled stones in relation to the incidence of complicated gallstone disease, aberrant ultrasound findings, and abnormal histopathological reports to predict risk factors for gallbladder perforation and stone spillage. Mention of any special effort made to locate and retrieve the spilled stones during LC, any change in the duration of postoperative antibiotics to counteract the increased risk of infective complications consequent to intraoperative spillage of bile and stones would have been immensely beneficial to the numerous readers keen on mastering the art of this common laparoscopic procedure. The author has summarized the study with a list of suggestions to reduce the rate of stone spillage during LC. Few other additions to this list can be as follows: secure grasping of the neck of the excised gallbladder along with the cystic duct clip during extraction, adequate enlargement of the port site for smooth extrication followed by meticulous examination of the retrieved specimen for integrity of the gallbladder wall. Any defect in the wall should prompt repeat inspection of all the relevant intra-peritoneal recesses as well as the path of extrication of the gallbladder.

SU‐E‐T‐264: Independent Quality Control and Quality Assurance Programs for IMRT

Purpose: Recently, radiotherapy for cancer advances to the highly precise treatment by various technical progresses. The highly precise radiotherapy that seems to be intensity modulation radiation therapy (IMRT) popularizes rapidly now. Therefore high technology of radiotherapy is demanded, and the quality control / quality assurance (QC / QA) is needed. In this study, it is a purpose to make the third‐party evaluation program to perform the radiotherapy that is safe from IMRT. Methods: The measurement was executed with an anthropomorphic IMRT phantom by the on‐site visit. The IMRT phantom was divided into a phantom shell and a module. The IMRT treatment plan was drafted by each institution to satisfy the following optimization conditions. (1) The D95 prescription (PTV) was 2Gy. (2) The PTV maximum dose was considered to be less than 110 %. (3) Organ at risk (OAR) was considered to be less than 60 %. The dose inspection for a drafted IMRT treatment plan was executed with the ionization‐chamber dosimetry module and the film dosimetry module. Results: The evaluation of the absorbed dose was executed for two points in PTV. In addition, the dose distribution measured axial, coronal, and sagittal side with a film. For these measurement sides, the evaluation of the position gap was achieved in the part that the dose gradient became precipitous. For the ionization‐chamber dosimeter, the differences at two points in PTV were less than ±3 %. For the dose distribution with the films, the differences for the position gap were less than ±2 mm. Conclusions: In this study, it was developed the phantom for inspection and measurement machinery to assure of the quality for IMRT, and the third‐party evaluation program was made. In the future, it will be necessary to repeat inspection in plural institutions to raise the reliability of the inspection result.

Damage tolerance analysis of the North American SNJ-6 wing lower attachment angle

This paper presents the damage tolerance analysis (DTA) work undertaken by the National Research Council Canada Institute for Aerospace Research (NRC–IAR) for the SNJ-6 wing lower attachment angles and the recommendations on a suitable repeat inspection interval for different usage and nondestructive inspection (NDI) capabilities. NRC–IAR carried out flight and laboratory testing to support the DTA work. Crack growth predictions were conducted using two different MIL-A-008866B spectra (basic and advanced trainer class spectra), three initial crack sizes (0.60, 0.40, and 0.25 in.), and four spectrum clipping values (5.67g, 5.00g, 4.50g, and 4.00g). A total of 24 crack growth scenarios were analyzed. A critical input to the analysis was the aspect ratio of surface crack length to crack depth, which was determined from fractographic images of the failed component. The crack growth and residual strength evaluations estimated the remaining time to failure in a broad range from 1572 h (advanced trainer; maximum...

Impact of measurement error on container inspection policies at port-of-entry

Containers arriving at a port-of-entry are inspected using sensors and devices to detect drugs, weapons, nuclear materials and other illegal cargo. Measurement errors associated with the inspection process may result in higher misclassification of containers. In this paper, we propose and formulate three inspection policies for containers at port-of-entry assuming the presence of sensor measurement errors. The optimization of the policies is carried out and the performance of each in terms of misclassification probabilities is compared. In each of the policies, the optimum settings are determined by minimizing the probability of false rejection while limiting the probability of false acceptance to a specified tolerance level. The results show that repeat inspections improve performance in terms of correct container classification. Expressions are presented for container misclassification in a single station, as well as in systems with several inspection stations arranged in different configurations such as series, parallel, series-parallel and parallel-series.

Are children attending child play areas at risk of infectious diseases? What can be done?

Child play areas can pose a risk to children of infectious diseases. The prolonged presence of micro-organisms in the environment has already been established. In order to quantify this risk, specific studies are required when carrying out a risk assessment. In order to assess the microbiological hazard in play areas in Malta, a study was performed during 2005, which consisted of an examination of the hygienic practices carried out in play areas by means of face-to-face interviews; inspections of the premises; environmental sampling and testing, and a study on the awareness and attitudes of parents to risk factors (face-to-face interviews). Follow up studies were performed after recommendations on risk management were provided. Overall, the hygienic practices in play areas were satisfactory. Of the premises 66% were licensed, 55% of the food handlers were registered, appropriate cooking and cooling facilities were available for most of the premises, temperature control records were available at 80% of premises, 60% were using disinfectant for cleaning play area surfaces and monitoring of refrigerated vehicles was carried out by 60%. There was an overall improvement after recommendations were given. At the first inspection, 67% of the premises were categorized as being fair and 33% as being good. On repeat inspection, after recommendations were made, the grading of the premises were: excellent 7%, satisfactory 33%, good 53% and fair 7%. The results of the environmental swabs taken had low counts of indicator organisms indicating a good overall hygienic condition. Parents stated that 58% of the areas were in good hygienic condition but lacked adequate hand-washing facilities for children. All parents agreed with the importance of hand hygiene and that infectious diseases can be transmitted via contaminated objects and from one person to another. An effective control strategy needs to be implemented involving all stakeholders to ensure that effective hygienic practices in play areas are available to protect children from infectious diseases.

Repeat inspection planning using dynamic programming

In this paper we propose a dynamic programming approach to the problem of determination of the inspection sequence of multi-characteristic critical components, and the number of repeat inspection for each characteristic. The model presented here considers the case of several classification of a product by an inspector. An inspector could classify a product as non-defective, to be reworked, or to be scrapped, with respect to a certain characteristic. The model accounts as well for possible misclassification by the inspector. The dynamic programming algorithm searches for a solution that minimizes the total cost of inspection per accepted component. The total cost includes the cost of false rejection of good items, the cost due to false acceptance of an item which is either reworkable or to be scrapped, the cost of inspection, and the cost of rework.

Impact of inspection errors on the performance measures of a general repeat inspection plan

Multi-characteristic critical components exist in many systems. Such components may be a part of an aircraft, space shuttle or a gas ignition system. An inspection plan for such components has been proposed in quality control that deals with several types of classification errors made by the inspector. In this paper, performance measures for this plan are defined and the statistical and economic impact of the several types of inspection errors on these measures is investigated. The impact of the errors is studied by conducting sensitivity analysis on the errors utilizing computer software which implements an algorithm that determines the optimal parameters of the model of the plan. The behaviour of the performance measures upon variation in the levels of errors is investigated. The results indicate that these errors have a considerable effect on the performance measures of the inspection plan.