Board Failure Research Articles

Using Osteopathic Medical School Institutional Data to Establish the Correlation Between Academic Performance and First-Time Board Pass Rates to Develop Academic Interventions for Students at Risk of First Board Failure

Using Osteopathic Medical School Institutional Data to Establish the Correlation Between Academic Performance and First-Time Board Pass Rates to Develop Academic Interventions for Students at Risk of First Board Failure

A Novel Framework for Optical Layer Device Board Failure Localization in Optical Transport Network

A Novel Framework for Optical Layer Device Board Failure Localization in Optical Transport Network

Does Failure Tolerance of the Board of Directors Affect Investment Efficiency?

Based on the perspective of failure tolerance, this paper measures the boards failure tolerance by whether the companys performance failing to meet the boards expectations leads to the mandatory replacement of managers. On this basis, the paper selects data from A-share listed companies in China from 2010 to 2022 to study the impact of board failure tolerance on corporate investment efficiency. The research finds that board failure tolerance can significantly improve corporate investment efficiency, both inhibiting over-investment and alleviating under-investment.

Fire resistance of gypsum-sheathed stud walls with an embedded steel door: Validation of a numerical approach

In the present study fire resistance tests of gypsum-sheathed stud walls were carried out and a fire safety steel door was embedded within the wall to address the mechanical interaction in between. A numerical approach was proposed based on coupled computational fluid dynamics/finite element method simulations to predict the temperatures and deformation. Since the heat transfer within the porous materials of the wall is crucial for the structural analysis, the numerical approach considered the conduction, chemical reactions, water vapour transport/phase change and thermal radiation. This detailed consideration showed good agreement to measured data for the wall and the door. It was highlighted, that the deformation of the door was well predicted, however, in the vicinity of the connections between the door and wall (e.g. door lock and bolts), the deformation was under-predicted. This was caused by the damaged connections, which were not considered in the simulation. The same effect was found for the wall. Although the numerical model was able to calculate the deformation behaviour, the predicted values were under-predicted due to the neglected failure of the gypsum boards. Furthermore, the numerical model was able to show the gap formation between the door and the wall with high accuracy.

SAG usage wear-resistant steel with rare retained austenite achieve trade-off between impact toughness and strength

The impact toughness is the key to determine the service life of high strength wear-resistant steel for the lining boards of large-scale semi-autogenous grinding mill (SAG). It is difficult to predict the impact fracture failure of lining boards when SAG is running, which can cause damage to equipment once it occurs. Therefore, novel high strength wear-resistant steel was designed to improve impact toughness in this study. It is interestingly found that the microstructure contained finer bainite/martensite, and rare retained austenite (around 2 vol.%), which achieved trade-off between impact toughness and strength after the optimal heat treatment scheme (900 °C normalizing → 900 °C quenching → 300 °C tempering). The element segregation of Al and Si was improved and the start temperature of martensitic transformation during quenching was reduced, resulting in the refinement of martensite laths. Thus, the higher density of high-angle grain boundary (HAGB) and dislocation were obtained, which contributed to excellent impact toughness. Based on the instrumented impact curve, the total impact energy can be divided into four parts: elastic deformation energy (Ee), plastic deformation energy (Ed), crack stable propagation energy (Ep1) and crack unstable propagation energy (Ep2). Traditional toughening mechanisms focus on Ep1, which was based on the tortuous crack propagation path. Our experimental results show that Ed was another effective control unit to ensure the toughness. The difference between Ed and Ep1 in improving absorption energy was discussed in detail by combining HAGB density and dislocation density.

When did the austerity era of European crisis management end? On the failure of National competitiveness boards

ABSTRACT The National Competitiveness Boards were supposed to become a central building block in European crisis management and enable European steering of wage developments. However, they failed and were institutionalized under the name ‘National Productivity Boards’ as largely non-binding advisory bodies. This article examines the policy-making process of the National Competitiveness Boards against the background of the EU’s current social and labor policy initiatives and argues from the perspective of a critical theory of European integration that the failure of the National Competitiveness Boards represented an important breaking point with the austerity policy continuity in the EU.

Fault Early Warning Model for High-Speed Railway Train Based on Feature Contribution and Causal Inference

The demands for model accuracy and computing efficiency in fault warning scenarios are increasing as high-speed railway train technology continues to advance. The black box model is difficult to interpret, making it impossible for this technology to be widely adopted in the railway industry, which has strict safety regulations. This paper proposes a fault early warning machine learning model based on feature contribution and causal inference. First, the contributions of the features are calculated through the Shapley additive explanations model. Then, causal relationships are discovered through causal inference models. Finally, data from causal and high-contribution time series are applied to the model. Ablation tests are conducted with the Naïve Bayes, Gradient Boosting Decision Tree, eXtreme Gradient Boosting, and other models in order to confirm the efficiency of the method based on early warning data regarding the on-site high-speed train traction equipment circuit board failure. The findings indicate that the strategy improves the evaluation markers, including the early warning accuracy, precision, recall, and F1 score, by an average of more than 10%. There is a 35% improvement in the computing efficiency, and the model can provide feature causal graph verification for expert product decision-making.

Experimental Study on the Effect of Hydraulic Deterioration of Different Drainage Systems on Lining Water Pressure

With the increasing operation time of tunnels, the drainage system cannot fulfil its proper function as a result of the deterioration of traditional waterproof and drainage systems (TWDS), such as the blockage of drainage blind pipes and the failure of drainage boards. Therefore, the lining bears a high water pressure and even causes disasters such as tunnel leakage and lining cracking. An effective solution to mitigate these issues is to adjust the tunnel drainage scheme. In view of this, a composite waterproof and drainage system (CWDS) is proposed in this paper. To verify the effectiveness of the proposed system, a series of model experiments were conducted to study the change law of the seepage field of two drainage systems under different blockage conditions. The study results showed that longitudinal blind pipe blockage caused a more significant increase in water pressure than circular blind pipe blockage. In the case of blind pipe blockage, the water pressure of the TWDS tunnels rise rapidly, while the CWDS tunnels could effectively drain and reduce pressure.

Simplified Fe modeling of the PyCubed PCB complete with components for CubeSat missions

CubeSat nano-satellites are, to date, the cheapest independent mean of bringing a payload into orbit. The most frequent cause of failure for this kind of launches is the mechanical failure of electronic boards or soldered electronic elements due to vibrations or shocks. For this reason, the numerical finite element design and experimental verification phases of printed circuit boards (PCBs) with soldered components are extremely delicate and critical in the assessment of the integrity of the boards during launch. In simulating the mechanical behaviour of PCBs it is important to consider the material properties, the geometry, and the type of components mounted on them. Possibly the most widely used open-source CubeSat PCBs are the PyCubed. While these avionics platforms, programmable entirely in Python, are radiation-tested and integrate many control features into a single low-cost PCB, they lack of a proper mechanical characterization. Indeed, we believe that the knowledge of the dynamic behaviour of this PCB is crucial to achieve high-reliability CubeSats and to improve the mission success rates. For this reason, this paper will not only provide a mechanical and physical characterization of the PyCuded open-source printed circuits; but above all, it will generate an innovative simplified and reliable numerical model of the PCB that reflects the dynamic behaviour of the complete motherboard of components during the launch. To support and to complete the analysis, numerical/experimental modal comparisons will be used to validate the proposed models. In this way, all designers of PyCubed PCBs will be able to simulate, as realistically as possible, the complete mechanical behaviour of the printed circuit in the presence of components, reducing time, costs, and design risks. The approach the authors proposed, could also be used to model other generic types of printed circuits boards.

Effect of contamination and relative humidity on the function of thyristor voltage monitoring board

In recent years, shutdown accidents caused by thyristor voltage monitoring (TVM) board failure have occurred several times in converter stations. With the increase of operation time, the working reliability problem of TVM board becomes a challenge to the safe operation. This paper studies the effects of pollution severity and relative humidity (RH) on the function of TVM board. The results show that the increase of RH can lead to the advance or even disappearance of check-back signals. Furthermore, the increase of pollution severity can decrease the failure RH threshold. Through simulation and equivalent experiment, it is verified that the resistance decrease of the voltage balancing resistor under the combined effect of contamination and RH is the main reason for the advance of check-back signals. According to the experiments, it is found that the upper surface contamination has a greater effect on the function of TVM board than the lower surface contamination, resulting in more decrease of the failure RH threshold. In addition, leakage current at different RH is also measured. Results show that the pulse peak of leakage current is closely related to check-back signals. When the pulse peak is too small or disappears, check-back signals also disappear, indicating that the TVM board fails.

Root Cause Analysis of a Printed Circuit Board (PCB) Failure in a Public Transport Communication System

A printed circuit board (PCB) is an essential element for practical circuit applications and its failure can inflict large financial costs and even safety concerns, especially if the PCB failure occurs prematurely and unexpectedly. Understanding the failure modes and even the failure mechanisms of a PCB failure are not sufficient to ensure the same failure will not occur again in subsequent operations with different batches of PCBs. The identification of the root cause is crucial to prevent the reoccurrence of the same failure. In this work, a step-by-step approach from customer returned and inventory reproduced boards to the root cause identification is described for an actual industry case where the failure is a PCB burn-out. The failure mechanism is found to be a conductive anodic filament (CAF) even though the PCB is CAF-resistant. The root cause is due to PCB de-penalization. A reliability verification to assure the effectiveness of the corrective action according to the identified root cause is shown to complete the case study. This work shows that a CAF-resistant PCB does not necessarily guarantee no CAF and PCB processes can render its CAF resistance ineffective.

School Boards’ Contributions on Community Secondary School Teachers’ Level of Motivation in Tanzania

The aim of this study was to investigate the contribution of school boards on teachers’ levels of motivation in community secondary schools in Moshi District Council, Tanzania. This was pursued under the research questions; which were to investigate the extent to which the school boards perform different teacher motivational strategies, the perceptions of teachers towards how the school boards motivates them, challenges and suggestions on how to improve the contribution of school boards on teachers’ levels of motivation and to determine the ways of overcoming the challenges in order to improve the performance of school boards on teachers’ levels of motivation. The study was guided by Motivation-Hygiene Theory of (1959). The researcher adopted concurrent design under the mixed methods approach which enabled the collection of qualitative and quantitative data at the same time for the purpose of understanding the problem in detail. The study targeted all heads of schools, teachers and board members from community secondary schools in Moshi District Council. Probability and nonprobability sampling techniques were used to select the study sample which consisted of 100 teachers, 10 heads of schools and 10 members of school boards to make a total number of 120 respondents. Questionnaires, document analysis schedule and interview guides were used to collect data. Descriptive and inferential statistics were used to analyze the quantitative data, frequencies, percentages and means. The hypothesis was tested by using independent sample t-test at 95% confidence level. Qualitative data were analyzed thematically. The study found out that the school boards do not do most of the practices that would contribute to teachers’ levels of motivation. Also teachers were found to have negative perception towards how the school boards motivate them. Results of hypothesis testing indicated no significant difference in the perception mean scores of male and female teachers whereas all of them felt to be demotivated by the school boards (p-value = 0.421). The findings revealed that lack of funds was pointed out as the main challenge for failure of the school boards to motivate teachers. The study recommended for proper fund raising so as to make the schools to have adequate budget for teachers motivation so as to enable teachers to give out their best.

Experimental and numerical studies on the fire-resistance behaviors of critical walls and columns in modular steel buildings

Modular steel construction (MSC) comprises off-site manufactured modules that are assembled on-site. When joining two modules together, double-layer wall systems and grouped columns are present at the junction regions, and different fire-proof measures are induced for critical walls and columns in modular steel buildings. In this study, experimental studies on the fire resistance of critical columns, load-bearing walls and non-load-bearing walls in a modular steel building were conducted to obtain the practical fire resistance performance. Temperature developments across the wall and column sections were measured and analyzed to determine the fire damage developments. The fire resistance ratings (FRRs) of different fire-proof measures were evaluated. The double-layer partition wall system and the load bearing wall system failed by the integrity failure criterion. The wall specimens all experienced the fall-off failure of fire side gypsum boards and severe ablation of the mineral wool insulation. The grouped columns with one layer of gypsum board and mineral wool insulation also experienced early gypsum board failure and a short fire-resistance rating. Based on the test results and literature reviews, suitable thermal properties for gypsum boards and mineral wool insulation were determined. The failure modeling methods for gypsum boards and mineral wool insulation were also defined. The established FE models can effectively predict the temperature developments across the section of wall and grouped column specimens. This paper provided useful fire test data for the fire proofing design of structural walls and columns in modular steel buildings, and offered rational thermal modeling methods for structural components considering the failure of commonly used fire proofing materials.

Finding Shorted Components on Printed Circuit Boards by Infrared-Based Direct Current Injection Method

Abstract This article explains how to find shorted components on PCB assemblies using infrared-based direct current injection, a nondestructive method that has several advantages over magnetic microscopy and voltage drop measurement techniques. An application example involving a power board failure is also provided.

Can ACGME Milestones predict surgical specialty board passage: an example in Obstetrics and Gynecology.

Background:Multiple tools including Accreditation Council for Graduate Medical Education (ACGME) standardized milestones can be utilized to assess trainee and residency program performance. However, little is known regarding the objective validation of these tools in predicting written board passage.Methods:In this retrospective study, data was gathered on n = 45 Wayne State University Obstetrics and Gynecology program graduates over the five-year period ending July 2018. United States Medical Licensing Examination (USMLE) scores, Council on Resident Education in Obstetrics and Gynecology (CREOG) in-training scores and ACGME milestones were used to predict American Board of Obstetrics and Gynecology (ABOG) board passage success on first attempt. Significance was set at p < 0.05.Results:Written board passage was associated with average CREOGs (p = 0.01) and milestones (p = 0.008) while USMLE1 was not significantly associated (p = 0.055). USMLE1 <217 (Positive predictive value (PPV) = 96%). CREOGs <197 (PPV = 100%) and milestones <3.25 (PPV = 100%), particularly practice-based learning and systems-based practice milestones were most strongly correlated with board failure. Using a combination of these two milestones, it is possible to correctly predict board passage using our model (PPV = 86%).Discussion:This study is the first validating the utility of milestones in a surgical specialty by demonstrating their ability to predict board passage. Residents with CREOGs or milestones below thresholds are at risk for board failure and may warrant early intervention.

58. ENTER THE MATRIX; A STANDARDIZED, ACCOUNTABLE APPROACH TO RESIDENT BOARD PREPARATION

Background Balancing clinical and board relevant education is a common struggle for residency programs. The ACGME mandates that programs maintain a > 70% first-time board pass rate but does not dictate how this is achieved. In-training exam (ITE) scores are reliable predictors of certifying board scores, but remediation success remains variable within and across institutions. Our program developed an educational aide, “the Matrix”, to guide and hold residents accountable for board preparation with flexible study activities based on individual learning preferences. It provides a starting point for determining remediation need and activities for those at risk of board failure. Objective Develop an educational aide based on adult learning theory to improve board pass rates of categorical pediatric residents. Methods Beginning intern year, pediatric residents completed the intervention “Matrix” throughout the academic year, with learning activities including practice question banks, article reviews and didactic attendance (Exhibit A). Residents discussed “Matrix” compliance with advisors every 3 months over 3 years. Board pass rate of residents for the 3 years after institution of the matrix is compared to prior 5 years of pass/fail data. Results First-time board pass or failure data was obtained for 60 residents over an 8-year period and divided into a pre- and post-intervention group (36 control and 24 intervention subjects). Pre-intervention had a composite pass rate of 70% compared to the intervention group with a pass rate of 92%, which is statistically significant (p value 0.01). Conclusion Our program has early success in increasing yearly board pass rates. Fewer have failed in the past 3 years post-intervention than in the 1 year prior. Adult learners require self-driven, relevant methods of study. Those at risk for exam failure need accountability. Applying these concepts to resident education improved pass rates with a small resident cohort taking the certifying boards. Our aide is easily adapted by other intuitions looking for a flexible but standardized method of board preparation.

An experimental study of carbonyl powder power inductor cracking during reflow process

PurposeIn surface mount assembly (SMA) process, small components are subjected to high temperature variations, which result in components’ deformation and cracking. Because of this phenomenon, cracks are formed in the body of carbonyl powder ceramic inductor (CPCI) in the preheat and cooling stages of the reflow oven. These cracks become the main cause of board failure in the ageing process. The purpose of this paper is to ascertain the thermal stress, thermal expansion of carbonyl iron ceramics and its effects on crack commencement and proliferation in the preheat stage of reflow oven. Moreover, this paper also categorized and suggested important parameters of reflow profile that could be used to eliminate these thermal shock failures.Design/methodology/approachIn this paper, two different reflow profiles were studied that evaluate the thermal shock of CPCI during varying ΔT at the preheat zone of the reflow oven. In the first profile, the change in temperature ΔT at preheat zone was set to 3.26°C/s, which has resulted in a number of device failures because of migration of micro cracks through the CPCI. In the second profile, this ΔT at preheat stage is minimized to 2.06°C/s that eliminated the thermal stresses; hence, the failure rates were significantly reduced.FindingsTMPC0618H series lead (Pb)-free CPCI is selected for this study and its thermal expansion and thermal shock are observed in the reflow process. It is inferred from the results that high ΔT at preheat zone generates cracks in the carbonyl powder-type ceramics that cause device failure in the board ageing process. Comparing materials, carbonyl powder ceramic components are less resistant to thermal shock and a lower rate of temperature change is desirable.Originality/valueThe proposed study presents an experimental analysis for mitigating the thermal shock defects. The realization of the proposed approach is validated with experimental data from the printed circuit boards manufacturing process.

Failure mechanism of lead-free component boards in thermomechanical test based on recrystallization enhanced cracking

The purpose of this paper is to make a comprehensive understanding of the trends between the lifetime and the thermomechanical test setup parameters, based on the physical failure mechanism of SnAgCu solder interconnections in the component boards. The thermomechanical tests, including thermal cycling and thermal shock, were employed to investigate the failure of the component boards under different loading conditions. The in situ observation during the thermomechanical tests was employed to study the microstructure evolution and the crack propagation of solder interconnections. Electrical failures of the component boards under all setup conditions are mainly caused by the cracks, which propagate along the continuous network of the high-angle grain boundaries produced by the distinguished recrystallization of solder interconnections. The propagation of cracks is highly dependent on the expansion of the recrystallized volume in the solder interconnections. In addition, the expansion of the recrystallization would be influenced by the setup parameters of the thermomechanical test. The paper discusses the relationship among the four factors of the lifetime, the crack growth, the restoration phenomenon and the test setup parameters, in order to explain the complicated trend between the component board lifetime and the setup parameters.

S137. LEFT HEMISPHERE MEG DEFICIT IN PITCH AND DURATION MISMATCH NEGATIVITY IN FIRST EPISODE PSYCHOSIS

BackgroundMismatch negativity (MMN) is an event-related potential (ERP) that is severely impaired in long-term schizophrenia. However, though largely debated, numerous electroencephalography (EEG) studies suggest that MMN is less reduced in individuals at their first episode of psychosis (FEP). Pitch MMN (pMMN) is not reduced, although duration MMN (dMMN) may be reduced compared to healthy controls (HC), and may show left hemisphere deficits early on. Few MMN studies in FEP have utilized magnetoencephalography (MEG). MEG could potentially be more sensitive to circumscribed differences, given its ability to more effectively localize MMN sources within the auditory cortex. Using MEG, we compared pMMN and dMMN between FEP and HC to identify potential source location- and timing-dependent differences in early disease course.MethodsSimultaneous MEG and EEG recordings of pMMN and dMMN were obtained with an oddball paradigm from 15 FEP and 19 HC. Of those, 12 FEP and 11 HC had usable EEG recordings, with the remainder lost due to a circuit board failure. MMN was calculated by subtraction of the sensor-space average to the standard tones from the average to the deviant tones. For EEG, mean amplitudes across fronto-central electrodes (F1, Fz, F2, FC1, FCz, FC2) were calculated over a 30 msec window at group peak latency. For MEG data, source activity was determined in Brainstorm using minimum norm estimation, multisphere head models, and individual MRI cortical surface reconstructions. Using the HCP Brain Atlas, regions of interest (ROIs) were determined based on areas of peak activity at two time windows for each task: an Early time window of 105–115 ms for both pMMN and dMMN, and a Late time window of 125–135 ms for pMMN and 155–165 ms for dMMN. Mean amplitudes were calculated over six auditory cortex ROIs: A1, Brodmann’s Area 43, Brodmann’s Area 52, Lateral Belt, Medial Belt, and Parabelt. Mixed-model ANOVA was then used to compare groups, regions, hemispheres, time windows, and tasks using SPSS software.ResultsFor EEG peak MMNs, there were no significant differences between groups in pMMN or dMMN (p’s > 0.1). For MEG sources, however, ANOVA indicated a Region x Hemisphere x Group interaction (p = 0.038), but no significant regional differences between Pitch and Duration or for either Early or Late time windows (p’s > 0.1). When ROI data were averaged across tasks and time windows, the right hemisphere showed no difference between groups, whereas the left hemisphere showed a trend for reduced MMN activity in FEP (p = 0.069). Post-hoc comparisons of the six left hemisphere ROIs revealed that all regions but Brodmann’s Area 43 showed significant reduction in FEP (p’s < 0.05).DiscussionThese findings support previous literature that indicate relatively preserved EEG scalp measures of MMN in FEP. However, the MEG source data indicate a deficit in the left hemisphere auditory cortex of FEP. This left hemisphere reduction was observed in 5 out of 6 source regions and at both time windows. This suggests broad left hemisphere auditory cortex pathophysiology early in disease course to which EEG may be relatively less sensitive by comparison with MEG. In conclusion, FEP may be associated with a selective left hemisphere MMN deficit in auditory regions on the superior temporal plane, but not the opercular cortex (i.e. Brodmann’s Area 43).

Experimental Study of Shear Behavior of Rock Joints under Two Types of Boundary Conditions: Constant Normal Load and Constant Normal Stiffness

Shear destruction of rock mass along weakened planes is one of the main reasons of the failure of career boards, underground workings and rock slopes. The paper deals with laboratory testing of rock joints under direct shear loading. Special test and measurement complex was created to study deformation and strength characteristics of rock joints. Test specimens were made from single slab of sandstone of homogeneous structure. Shear tests have been conducted under constant normal load (CNL) and constant normal stiffness (CNS) boundary conditions at three values of normal compressive stress: 0.5 MPa, 1.2 MPa and 1.8 MPa. The analysis of test results allowed to reveal patterns of changes of deformation-strength properties of rock joints depending on the level of normal load, boundary conditions and roughness values. The ultimate shear stress is always higher under CNS boundary condition than CNL for the same values of normal compressive stress. Shear stress practically retains constant value after reaching the ultimate stress under CNL boundary conditions and it decreases under CNS conditions. The values of ultimate shear stresses, shear modulus and the length of linear section on “shear stress–shear displacement” curve increases with increasing surface roughness at the equal levels of normal compressive stress.