Probable Cause Of Damage Research Articles

Research on Hovercraft – Fatigue Cracks in the Engine Frame

Abstract Rescue patrol hovercrafts must meet the basic condition – high reliability of use in extreme conditions. The introduction to the work shows damage to the propulsion system and the fan tunnel structure resulting from a fatigue fracture of the attachment wound to the propulsion unit hull. In this paper, the author describes some ways of improving the engine frame structure. In the first phase of the exploitation crack testing of the hovercraft frame, the probable causes of damage were determined. The necessary output data for analysis of the load course were obtained from the operating documentation. The approximate number of variable load cycles acting on the frame truss rod was determined. Using the comparative testing methods, the service life of the frame was estimated. Probable resonance frequencies of the vibrating bars in the truss were determined. Vibration tests of the power transmission assemblies were carried out, which allowed to determine the amplitudes and frequencies of free vibrations. Finally, a modification of the frame shifting the resonant frequency range was proposed. In conclusions, changes to the design and a schedule of inspections were proposed. The newly designed engine frame should have an extended service life.

Анализ нагруженности кожуха зубчатой передачи электровоза при условии ослабления затяжки болтов его крепления к тяговому двигателю

Objective: To study the dependence of the numerical values of the bearing reactions occurring in the bolted fasteners of the gear casing (GC) on the conditions of its fastening to the traction motor. To show the resulting redistribution of the bearing reaction values in the case of the lack of load bearing in one or two bolted fasteners from the three existing design ones. To calculate the equivalent stresses that appear in the gear casing structure under various abnormal conditions of its fastening to the traction motor under static loading. Methods: The equations of statics were used for the spatial system of forces, including three vertical bearing reactions and the weight of the casing itself. To study the stress-strain state of the casing in the case of its static loading, the finite element method was used, implemented in the ANSYS Workbench software package. Results: The cause of damage to the GC during operation has been found associated with its design flaws. Calculation formulas have been obtained for determining the vertical bearing reactions of the GC. The need to take into account the GC loading in the case of redistribution of loads due to the loosening of its fastening bolts has been found. The need to improve the design of the gear casing has been indicated. Practical importance: The probable cause of damage to the GC during operation has been found. A method is proposed for assessing the GC loading in the case of redistribution of loads between its bearing points.

Optimising the transportation of avocados from farm to packhouse using Bayesian networks

Unnecessary losses occur due to the postharvest transportation of avocados from farm to packhouse. Damage done to avocados may only become visible during later stages of the fruit's ripening, making it difficult to detect damage during the early stages of the supply chain. This study looks at where improvements can be made, specifically identifying the hazards occurring between harvest and the packhouse, by means of a Bayesian network. The network was populated using data collected from the farm using civiltronics, investigating hazards by consulting literature and using expert elicitation to better understand the identified hazards and their effect. The study concluded that the most probable cause of damage results from the overall tree condition, the delay in transportation, picking techniques and unloading procedures at the packhouse. The Bayesian network is a powerful tool which can be updated with evidence from the farmers once improvements are made to reassess the network.

Metallurgical analysis of the causes of failure of the hardening furnace conveyor belt

Purpose: The aim of the tests was to analyze the microstructure and mechanical properties of a section of the hardening furnace conveyor belt serviced at the temperature of 880-920°C in the carburizing atmosphere, in the context of determining the probable causes of its failure. Design/methodology/approach: The scope of performed tests included: chemical composition analysis of the steel and particles, microstructure investigated using optical and scanning electron microscopy, X-ray phase analysis. Findings: The analysis of the chemical composition showed that the examined material was austenitic steel X15CrNiSi25-21 (S310). Performed metallurgical tests showed that after the service the examined steel was characterized by austenitic structure with numerous precipitates of diverse morphology. In the structure the sigma phase particles and probably the M23C6 carbides precipitates were observed. The continuous grid of precipitates on the boundaries of grains (mainly the sigma phase) and the influence of the cyclic changing heat loads (or thermo-mechanical loads) were the main causes of failure of the analysed detail. Research limitations/implications: The aim of the work was to determine the probable causes of damage of the material used for a conveyor belt of a hardening furnace. Practical implications: The results of investigation and analysis of the metallographic of het-resisting austenitic steel X15CrNiSi25-21 (S310) after service at the temperature of 880-920°C are presented. Originality/value: The paper presents the results of research on the microstructure and mechanical properties of the section of hardening furnace conveyor belt made of creepresisting austenitic steel. The aim of the performed tests was to determine the probable causes of damage of the analysed detail.

Probable cause of damage to the panel of microalgae bioreactor building façade: Hypothetical evaluation

Having a noticeable role in CO2 sequestration and O2 production, microalgae as precious sources of the third-generation biofuel, offer various advantages for energy efficient architecture. Although biofuel production from microalgae biomass has a considerable research background, integrating microalgae culture system with building façade is in its infancy. It is mainly due to the fact that there is only one real building named BIQ house adopting the bioreactor façade technology constructed in Germany, 2013. Hence, there are various challenges associated with this newly emerged technology. This paper aims to detect and estimate the probable causes of damage to microalgae photobioreactor panels integrated with building façade known as SolarLeaf. In order to realize the paper key objective, by comprehensively studying the literature review, surveying and interviewing with the experts, the factors causing damage to bioreactors were recognized and categorized.Based on the results, the main damages are classified as internal and external. Internal causes include bio/chemical and structural factors, while external ones involve climatic and operational/constructional ones. These are the fundamental damage categories of microalgae façade systems that architects and engineers should get familiar with in order to meet and consider the defects developed in the bioreactor panel structure during the design and construction process.

Retina assessment by optical coherence tomography of diabetic dogs

ABSTRACT: Diabetes mellitus is one of the most common endocrine disorders characterized by relative or absolute lack of insulin; this can lead to several ocular manifestations, among them diabetic retinopathy and cataracts. Diabetic retinopathy (DR) is a microangiopathy that involves retinal precapillary arterioles, postcapillary venules, and large vessels, causing them to be functionally and anatomically incompetent. Hyperglycemia seems to be the most probable cause of damage to the retina due to interference in cellular metabolism and transduction processes. The aim of this study was to evaluate retinal thickness in eight diabetic dogs, four females and four males of different breeds and ages ranging from 6 to 15 years, by optical coherence tomography (OCT) and to compare them with non-diabetic dogs. Assessment provided by OCT in diabetic dogs showed retinal layers thinning and loss of stratification when compared to non-diabetic dogs (198μm versus 219μm respectively), with statistical significance (p=0.008). OCT images may suggest that diabetes mellitus causes retinal neuropathy in dogs, as also seen in diabetic humans.

A numerical simulation of static stiffness and strength of circular saw blade

The paper deals with the evaluation of the static stiffness and strength, which are critical parameters affecting the stability of the machining process but also the safety and durability of the wood cutting tools. Circular saw blade models for the purpose of computer numerical simulation were proposed using finite element methods, and verified in earlier research. Deformation response was observed, depending on the input parameters correlating to the saw blade woodworking conditions. The strength of the saw blade was compared with the different clamping methods and different thickness of the circular saw blade. An article gives a disturbing finding how minor change in the quality of the circular saw blade clamping, specifically one degree of misalignment, leads to critical states and probable cause of damage.

Polymorphism in the serotonin transporter protein gene in Maltese dogs with degenerative mitral valve disease.

Degenerative mitral valve disease (DMVD) is the most commonly acquired cardiac disease in dogs. This study evaluated the relationship between genetic variations in the serotonin transporter (SERT) gene of Maltese dogs and DMVD. Genomic DNA was extracted from blood samples collected from 20 client-owned DMVD Maltese dogs and 10 healthy control dogs, and each exon of the SERT gene was amplified via polymerase chain reaction. The resulting genetic sequences were aligned and analyzed for variations by comparing with reference sequences; the predicted secondary structures of these variations were modeled and cross-verified by applying computational methods. Genetic variations, including five nonsynonymous genetic variations, were detected in five exons. Protein structure and function of the five nonsynonymous genetic variations were predicted. Three of the five polymorphisms were predicted to be probable causes of damage to protein function and confirmed by protein structure model verification. This study identified six polymorphisms of the SERT gene in Maltese dogs with DMVD, suggesting an association between the SERT gene and canine DMVD. This is the first study of SERT mutation in Maltese dogs with DMVD and is considered a pilot study into clinical genetic examination for early DMVD diagnosis.

Probable causes of damage of heat-exchange tubes of low-pressure-exchanges of PND-3 type and repair methods

The structures of low-pressure heaters (LPH), which are installed at nuclear power plants with the K-1000-60/1500 type turbine plants are considered. It was revealed that only the PND-3 type low-pressure heaters have the damages of the heat exchange tubes. For a short operation life, the number of the damaged heat-exchange tubes of PND-3 is approximately 50 pcs for Kalinin NPP and 100–150 pcs for Balakovo NPP. The low-pressure heaters were manufactured at AO Ural Plant of Chemical Machine-Building “Uralkhimmash,” OAO Taganrog Boiler-Making Works “Krasny Kotelshchik,” and Vitkovice Machinery Group, but the damage nature of the heat-exchange tubes is identical for all PND-3. The damages occur in the place of passage of the heat exchange tubes through the first, the second, and the third partitions over the lower tube plate (the first path of the turbine condensate). Hydraulic shocks can be one of the possible causes of the damage of the heat-exchange tubes of PND-3. The analysis of the average thermal and dynamic loads of the tube systems of PND-1–PND-4 revealed that PND-3 by the thermal power are loaded 1.4–1.6 times and by the dynamic effects are loaded 1.8–2.0 times more than the remaining LPHs. Another possible cause of damage can be the cascaded drain of the separate into PND-4 and then through the drainage heat exchange into PND-3. An additional factor can be the structure of the condensate drainage unit. The advanced system of the heating steam flow and pumping scheme of the separate drain using the existing drainage pumps of PND-3 for K-1000-60/1500 turbine plants for Balakovo and Kalinin NPPs were proposed. The considered decisions make it possible to reduce the flow rate of the heating steam condensate from PND-3 into PND-4 and the speed of the heating steam in the tube space of PND-3 and eliminate the occurrence of hydraulic shocks and damages of the heat exchanger tubes.

Roadside Alligators and the UMTRI Tire Debris Survey

Roadside alligators (also known as tire debris) are those unsightly shreds or fragments of rubber occasionally found on the nation's highways. The typical road user misunderstands the nature, extent, and contributing factors precipitating their formation. During the summer of 2007, the University of Michigan Transportation Research Institute conducted a national tire debris survey that involved the collection of 85,000 pounds of rubber and that provided 300 casings and 1,196 debris items for subsequent failure analysis. This paper discusses tire debris within the context of roadside litter, presents the tire debris survey methodology, and discusses the survey results. Overall, where the original equipment tread or retread status could be determined, original equipment accounted for 60%, and retreads accounted for 40% of the tire casings tested. For tire fragments, the status was 21% (original equipment) and 79% (retread). There was also a strong similarity for these same tire items in the ranking of probable causes of damage or failure. Road hazard or maintenance and operational factors were two of the top three probable causes of damage or failure. This result suggests that the majority of tire debris items found on the nation's highways is not a result of manufacturing or process deficiencies. However, two primary challenges remain: first, increasing public awareness about the origins, characteristics, and impacts of tire debris and, second, ensuring adherence to the highest standards in commercial driver truck operations and associated tire maintenance. Resolving these challenges can significantly reduce roadside tire debris and correct the understanding of highway users about the origins of the roadside alligator.

Investigation of probable cause of damage of steam drum of naphtha cracking furnace

This investigation was primarily aimed to examine the probable causes of damage in steam drum of heat recovery boiler in a naphtha cracking plant. Large number of cracks was detected of varying length on the inner surface of the drums. Preliminary visual examination, magnetic particle inspection, in situ metallographic examinations were carried out at the site. Detailed optical microscopic analysis along with scanning electron microscopic (SEM) and transmission electron microscopic (TEM) examinations on the scooped samples from different locations of the steam drum were carried out to understand the metallurgical reasons for damage. Stress analysis was carried out on the steam drum on the basis of strength for the internal pressure. Finally, it was concluded that metallurgical factors as well as operating conditions were responsible for the cause of damage in the steam drum.

Phytochemical analysis of the antioxidant properties of Silybum marianum L

A growing body of evidence supports lipid peroxidation as having a role in the pathogenesis of liver disease. Although the probable cause of damage to human hepatocytes may be multifactorial, free radicals have been implicated in a variety of liver diseases, particularly in the presence of iron overload and toxic substances such as ethanol. Consequently, antioxidants, particularly those of plant origin such as flavonoids, may help to reduce the risk of developing these diseases. Silybum (S.) marianum, a medicinal plant widely used in traditional European medicine for the treatment of liver disorders, was evaluated for antioxidant activity. Thin layer chromatography and High Performance Liquid Chromatography analyses of crude extract of the plant confirmed the presence of a number of flavonoids reported in the literature. The antioxidant activity of these flavonoids was measured through inhibition of lipid peroxidation and 1, 1-diphenyl-2- picrylhydrazyl radical scavenging. The crude plant extract showed marked antioxidant activity in both assays. These results suggest that S. marianum contains flavonoids with antioxidant activity, capable of inhibiting or scavenging free radicals, thus supporting its traditional use as a hepatoprotective agent.

An Integrated Approach to Risk Assessments and Condition Surveys

This article discusses the integration of risk assessment and collection condition surveys, with reference to the uncertainties inherent in each of these two procedures. While condition surveys provide information on a collection's immediate condition, risk assessments add predictive aspects on the collection's potential for deterioration. Looking at probable causes of damage in a condition assessment can provide a link to the agents of deterioration examined in a risk assessment. Combining these two complementary assessments can provide useful insights and Clarify priorities for the collection's management goals. Comparison of the advantages and disadvantages of two types of evaluation processes in visual perception, top-down and bottom-up, are discussed as they apply to the integration of the two assessments. Additionally, the article describes the use of an integrated assessment approach for a survey of the English Heritage collections. In conclusion, it was found that integrating condition surveys with risk assessments could increase the knowledge and understanding of current and future expectations of a collection.

Sexual Dysfunction Caused by Injuries of the Cervical Spinal Cord Without Paralysis

Loss of sexual desire and impairment of sexual function in patients with symptoms of cervical spinal cord involvement without paralysis were found in 85 patients of both sexes in a series of 2076 consecutive patients seen during a 13-year period. History of trauma was given by 79 patients. Compression of the spinal cord and nerve roots by disc herniation, contusion, and/or edema from hyperextension and flexion injuries in the patients with sexual dysfunction was the most probable cause of damage to the intermediolateral column of cells in the lateral horn. In another study, sections of the spinal cords of 11 patients, who had been subjected to lower cervical cordotomies, showed destruction of the lateral horn of the spinal cord in 3 patients who had experienced sexual dysfunction. Sexual function improved in 77% of patients with surgically treated cervical spinal cord injuries and in 26% of conservatively treated patients.

Evaluation of Flood Water Quality in the West Montalvo Field

Abstract One of the most important factors affecting success of waterflood performance is maintenance of water quality. Determining minimum water quality is difficult because water quality requirements are as varied as the formations to be flooded. Previously, attempts have been made to set quantitative standards based on simple tests for water quality. However, injection water quality is best measured by formation core flooding at conditions that model fullscale injection operations. While acceptability of source water can be determined in the laboratory by flooding formation core material, it is difficult to acquire representative water samples because of water instability. On-site core flooding at sand face injection temperature with water from a pilot treating plant minimizes water quality uncertainty and permits continuous, on-line screening for development of treating and filtering requirements. Water injection acceptability and pilot plant evaluation provide determination of corrosivity, filtration efficiency, treatment additive compatibility and treatment economics. This source water evaluation method improves waterflooding economics in two important ways:minimum treatment cost to maintain continuous injection without permeability decline is established; andthe possibility of injection well damage is reduced. Introduction An evaluation study of an injection water source is described. In addition to the usual determinations of bacterial activity and corrosivity, this on-site pilot plant study evaluated particle plugging tendency, scaling tendency, treating chemical compatibility and potential clay problems by formation core flooding at sand face injection temperature. The purpose was to provide an economic means of maintaining injectivity in West Montalvo field, Oxnard, Calif., by developing a chemical treatment and filtration system from core flood tests. Injection History Water injection in the West Montalvo field began in 1963, with the injection of produced brine into the McGrath pool. Immediate injection problems resulted from inadequate water treatment. In mid-1964, a shallow source well was drilled on the ocean shore to supply saline injection water for both the McGrath and Colonia pools. Water analysis and injection tests performed in the laboratory indicated the new water to be suitable after minor chemical treatment and filtration. Injection into a Colonia zone well began in Sept., 1964, at an average rate of 600 BWPD at 3,000 psig. However, the rate declined to 440 BWPD at 4,600 psia within 3 months. Injection wells continued to plug and required repeated acid stimulations to maintain injection (Fig. 1). Injection in the initial injector could not be maintained economically, and in April, 1966, the well was shut in. Reservoir characteristics peculiar to the Colonia zone were apparently part of the problem because injectivity was much better in the McGrath pool. The Colonia zone is a thick, non-marine, Oligocene section comprising a series of thin oil- and water-bearing sand lenses interbedded with shales. Petrographic analysis of core material indicated sufficient kaolinite. illite and montmorillonite to cause permeability damage from clay migration. Clay sensitivity and poor water quality were probable causes of damage to Colonia zone injectors; therefore, a flow test program was designed to evaluate injection problems. JPT P. 683ˆ