Critical Spots Research Articles

Design intent application to tolerance-based manufacturing system

Continuous shrinkage of the design rule in large-scale integrated circuit devices brings about greater difficulty in the manufacturing process. The keys to meeting small process margin are adequate extraction of critical dimension tolerance for each object, considering design intent in terms of electrical behavior, and assigning the tolerance for each process step. However, once the design data are converted to layout data and signed off, most of the design intent is abandoned and unrecognized in the process phase. Thus, uniform and redundant tolerance is used, and therefore, excess tolerance is assigned for some layouts. To solve the problem described above, a tolerance-based manufacturing system utilizing flexible layout-dependent speculation derived from design intent has been discussed. Using a 40-nm node test chip, electrically critical spots, such as timing, cross-talk noise, electromigration, with small margins are extracted, assigned to the physical layout, and utilized in the manufacturing process. The flow is applicable for optical proximity effect correction (OPC) turnaround time reduction, optimization of OPC/lithography compliance check (LCC) specification, and failure-analysis acceleration. Consequently, a design-intent-aware manufacturing system is promising for realizing proper process specifications and computational cost reduction, in addition to yield enhancement.

Testing of Acoustic Emission Technology to Detect Cracks and Corrosion in the Marine Environment

Real-time monitoring and detection of structural degradation helps in capturing the structural conditions of ships. The latest nondestructive testing (NDT) and sensor technologies will potentially be integrated into future generations of the structural integrity management program. This paper reports on a joint development project between Alaska Tanker Company, American Bureau of Shipping (ABS), and MISTRAS. The pilot project examined the viability of acoustic emission technology as a screening tool for surveys and inspection planning. Specifically, testing took place on a 32-year-old double-hull Trans Alaska Pipeline System (TAPS) trade tanker. The test demonstrated the possibility of adapting this technology in the identification of critical spots on a tanker in order to target inspections. This targeting will focus surveys and inspections on suspected areas, thus increasing efficiency of detecting structural degradation. The test has the potential to introduce new inspection procedures as the project undertakes the first commercial testing of the latest acoustic emission technology during a tanker's voyage.

An Immodest Proposal: Pedagogic Information Supports for Teachers

Background/Context Concerns about instructional quality have unleashed a frenzy of reform efforts, including changes in school governance, teacher recruitment, and curriculum, modification of teaching philosophies and procedures, stricter accountability management, and increased quests for scientific research information and guidance. These efforts have resulted in much hope but modest returns. We have middling success in educating our talented students and fail catastrophically with many others. Science and mathematics instruction are among our most critical weak spots. Urgent demand for technically competent people in the workplace and society calls for early relief from our educational discomforts. Purpose/Focus The essay examines how we can take advantage of the colossal scale of the American educational system to improve instruction. Although policy makers have persistently turned away from the fact, the same subject matter is taught in thousands of schools, year after year, and thousands of teachers face very similar instructional tasks. The huge scale of their efforts, coupled with progress in the instructive uses of digital devices, makes it sensible and economically feasible to provide teachers with powerful tools to serve their common needs. We examine requirements and possible configurations for such digital instructional tools and their uses, and we make some cost estimates. Research Design This is an analytic essay. Conclusions/Recommendations Substantial investment of technical and financial resources is proposed for the development of a pedagogic information support system (APIS) for critical courses or subject matter in which competent teachers are in short supply. These systems should be sufficiently comprehensive to cover all core components that a reasonable teacher might include, as well as instrumentally pedagogic elements. APISs are seen as loosely organized, highly redundant collections, in polymorphic digital forms, of explanations, demonstrations, simulations, interactive exercises, problems, examples, elaborations, integrative expositions, and motivational supports, as well as a deep, searchable information base. An APIS for a particular course would be sufficient to support inexperienced teachers and skillful veterans and could be used both with monitored class groups and supervised individual students. APIS can be expected to provide new opportunities for practical teacher education and to stimulate and coordinate instructional research.

High Speed Processing for Microelectronics and Photovoltaics

AbstractQ‐switched infrared, green, UV and DUV lasers are being used routinely for various microelectronics and photovoltaic manufacturing applications, such as ablation and cutting of dielectric materials, LED scribe and cleave processes in microelectronics, and scribing thin film solar cells.To create functional good results when micromachining any material, the laser energy density needs to be set higher than the material removal threshold and a reasonable laser beam spot overlap is required. The maximum scribing speed achieved using a system with a pulsed laser source therefore is usually limited by the laser repetition rate and the energy per pulse available at that repetition rate. For a given repetition rate, as processing speed increases the beam spot overlap decreases and at certain critical processing speed laser beam spots gets separated in space and continuous scribing of material is not possible. This fundamental limitation has to be solved in order to achieve faster processing speeds, higher throughput, and lower cost per part.To overcome this limitation in next generation laser processing systems, SpectraPhysics has developed and evaluated high repetition rate mode‐locked lasers as an alternative to Q‐switched lasers. Using a high average power mode‐locked laser operating at 80 MHz, we have been able to demonstrate processing speeds that are an order of magnitude higher in thin layers of select materials than that with current Q‐switched technology. The following article reviews results obtained for micromachining dielectrics, scribing and cleaving blue LEDs, and scribing different solar cell materials.

Metaphor and Maternity: Dante Gabriel Rossetti 's House of Life and Augusta Webster's Mother and Daughter

In Gabriel Rossetti and Late Victorian Sonnet Sequence, John Holmes recently discussed shaping influence of The House of Life (1870, 1881) on a wide range of authors, Christina Rossetti and Rupert Brooke to scarcely known Theo Marzials, George Barlow, and Rosa Newmarch. Augusta Webster, to whose posthumously published sonnet sequence Mother and Daughter (1895) Holmes devotes a brief section, sticks out as neither a familiar face nor a complete stranger. (1) When Webster's oeuvre was rediscovered in 1990s, critical interest initially focused on controversial female speakers of her dramatic monologues (Portraits, 1870): an infanticidal mother in Medea in Athens, a genteel prostitute in A Castaway, a bewitching temptress in Circe. The thematically much more conventional Mother and Daughter, by contrast, has been slow to make its way into scholarly publications. Dorothy Mermin was probably first to note that it extends emotional range of sonnet sequence beyond its traditional amatory concerns. (2) Angela Leighton and Alison Chapman also addressed sequence briefly in their surveys of Victorian poetry, and Florence Boos discussed it in more detail in her contribution to a study of Rossettis' literary legacy. (3) Despite pioneering insights she offers into works of several virtually unstudied late nineteenth-century female sonnet writers, Boos persistently refers to Webster's sequence as Mother and Child, thus inadvertently betraying just how unfamiliar most critics still are with work. To figure Rossetti's influence on Webster, Holmes and Boos both adopt metaphor of literary kinship. Boos quite conspicuously presents Webster, Mathilde Blind, Amy Levy, Olive Custance, Rosa Newmarch, and Michael Field in title of her essay as Dante Gabriel Rossetti's poetic daughters. Holmes's discussion of late Victorian women poets follows a chapter devoted to the sons of Gabriel, suggesting that women he goes on to consider belong to female lineage of Rossetti's poetic offspring. The adoption of genealogical vocabulary seems most apposite in this context since, as Harold Bloom has pointed out, from sons of Homer to sons of Ben Jonson, poetic influence [has] been described as a filial relationship. (4) Yet, by taking Rossetti's literary parentage for granted, Boos and Holmes create major critical blind spots. While they meticulously scan Mother and Daughter for Rossettian approaches to life, and death, profusion of references to birth, childhood, and maternity in The House of Life, which, in case of Webster, constitutes such an obvious point of comparison, remains largely undisclosed. In addition, although figuring of literary influence in terms of son- or daughter-ship may accord with distinct predilection that Rossetti, like so many of his predecessors and colleagues, had for trope, it does not necessarily do justice to Webster and her sequence. Most crucially, it obscures possibility of reading Mother and Daughter as a cogent critique of alienation of fundamentally female experiences, such as birth and motherhood, and of female body in general for use as metaphors of male creativity. Gabriel Rossetti's plan to compose The House of Life sprang Willowwood, a series of four sonnets that boldly rewrite Ovid's myth of Narcissus. The group heads all early drafts and manuscript versions of sequence, and was first published in 1869 in Fortnightly Review as sonnets 1 through 4 out of sixteen sonnets On Life, Love, and Death before taking its final position at heart of 1870 and 1881 printed editions. Critics have variously described it as addressing problem about love and hope of its fulfilment, recording the obsessive nature of desire for unity and fact that desire becomes even more obsessive after separation, and most recently, exploring homoerotic potential of Rossetti's vision of love, but it was probably William Michael Rossetti who best captured scope of Willowwood when he claimed that it is all about the pangs of severance. …

Rough collision in three-dimensional rigid multi-body systems

In the current paper, single point rough collision in three-dimensional rigid multibody systems is modelled. Coulomb's friction law and infinite tangential stiffness are assumed. Routh's incremental model with energetic coefficient of restitution is used. Equations of motion are developed by means of Lagrangian formulation. The non-linear equations of motion show that the contact point could continuously change its sliding direction or the sliding could halt and the non-sliding persists or it could restart along a new direction. All these possible sliding behaviours during impact are identified, conditions leading to each behaviour are specified, and an appropriate numerical procedure is suggested. Normal impulse at the contact point is considered the independent variable, as time-like, to carry out the numerical integrations of the equations of motion. A case of a four-degrees-of-freedom spatial robot that collides with its environment is investigated. Solutions describing the variation of collision variables are obtained. It is recognized that qualitative changes to all the variables occur whenever sliding velocity reaches its minimum value. These critical spots are identified, the associated abrupt variations in the impact variables are explored and the friction influence is observed.

How valid are parents' questionnaire responses regarding building characteristics, mouldy odour, and signs of moisture problems in Swedish homes?

Questionnaires are a cheap means of studying large populations but the information obtained from them is seldom validated. Earlier studies have reported both high and low levels of agreements between inspectors' observations and occupants' reports regarding home environmental factors that included moisture problems. The aim of this study was to validate information received from a questionnaire survey regarding building characteristics, mouldy odour, and signs of moisture problems in 390 Swedish homes. In a case control study on the association between home environmental factors and asthma/allergy among children, 390 homes were visited by trained inspectors for ocular inspection of visible moisture damage and perceptions of mouldy odour. Their observations were then compared with questionnaire reports collected 18-24 months earlier from the families. A high level of agreement was found between the inspectors' observations and the occupants' questionnaire reports on technical parameters. This included type of house, type of ventilation system, and foundation, particularly in single-family houses. There was low agreement regarding vinyl or linoleum floor coverings and indications of dampness and mouldy odour. However, the stronger the mouldy odour experienced by the inspector, the higher the level of agreement. The questionnaire was a quite reliable source regarding technical parameters of the home but not for dampness problems. The questionnaire was better for predicting buildings without problems than detecting problems of mouldy odour and visible indications of moisture. To increase the validity of future questionnaires, simple drawings or information on critical spots for dampness could be used.

Landslide risk analysis in the area North of Lisbon (Portugal): evaluation of direct and indirect costs resulting from a motorway disruption by slope movements

A risk analysis is developed for a test site located in the area north of Lisbon using a scenario of a temporary interruption of the motorway A9 due to a landslide of rotational or translational type. Landslide susceptibility is assessed at the regional scale independently for rotational and translational slides, comparing the landslide distribution with a set of assumed independent landslide predisposing factors. Susceptibility models are validated and classified through the computation of prediction rate curves based on the temporal partition of the landslide data sets. Landslide hazard maps are based on a scenario of future landslide occurrence for the next 27 years. These maps allow the definition of two critical areas on the motorway A9 with regards to landslide susceptibility. Direct costs associated with both critical spots are assessed taking into account the probable affected area of the motorway, and the reconstruction costs. Indirect costs derived from the traffic interruption are evaluated considering the alternatives paths to the motorway, and include costs resulting from: (1) additional fuel consumption; (2) decrease in tollgate income; and (3) loss of productive time. Results show that indirect costs may be 24 to 43 times higher than direct costs, assuming a temporary interruption of the motorway for 6 months.

A statistical measure of the non-proportionality of stresses – investigations and applications*

Abstract In mechanical engineering, fatigue assessment based on Finite Element analysis of components, where complex non-proportional loads are acting on, plays an important role in identifying critical spots, and predicting the lifetime, till crack initiation. In this contribution the life time analysis of a dynamically loaded crankshaft of a V6 diesel engine is demonstrated. Finite Element method, multi-body system simulation and an elasto-hydrodynamic simulation of the oil film have been combined for a modal analysis in the frequency domain. Based on these results a fatigue analysis follows to identify the critical engine speed range. In notches rotating principal stresses can be found, which reduce the lifetime significantly. To quantify the non-proportionality of stresses and the resulting decrease of the fatigue limit, a statistical measure originally proposed by Chu et al. is applied. The critical plane criterion has been used in conjunction with a stress based method (concept of synthetic S/N-curves, influence parameter concept) and linear damage accumulation according to Miner's rule.

Pathways for transfer and spreading of Aujeszky’s disease to carnivora

Aujeszky?s disease (Morbus Aujeszky) is an acute viral contagious disease occurring in a large number of domestic and wild animals. This epizootiological disease has been present in our country for quite some time now, and it has been increasingly frequently diagnosed in carnivora in the recent years. The objective of the investigations was to determine and establish the pathways for the transfer and the manner of spreading of the MA virus to carnivora. Epizootiological data on the appearance of MA, collected in the field, as well as an epizootiological report by the Serbian Ministry of Agriculture and of the Federal Ministry for Agriculture were used as material. Detailed epizootiological, clinical, pathomorphological, and laboratory analyses were performed in five critical spots for MA registered in the territory of Vojvodina province. We established the following pathways for the spread of the MA viral infection to carnivora: the consumption of thermally unprocessed swine carcasses, the consumption of thermally unprocessed pork originating from butcher shops or from regular slaughter on private farms, the consumption of viscera from emergency slaughtered sheep, cohabitation and contact with infected swine, and vaccination using a live vaccine contaminated with the MA virus.

Reliability demonstration test planning: A three dimensional consideration

Increasing customer demand for reliability, fierce market competition on time-to-market and cost, and highly reliable products are making reliability testing more challenging task. This paper presents a systematic approach for identifying critical elements (subsystems and components) of the system and deciding the types of test to be performed to demonstrate reliability. It decomposes the system into three dimensions, (i.e. physical, functional and time) and identifies critical elements in the design by allocating system level reliability to each candidate. The decomposition of system level reliability is achieved by using criticality index. The numerical value of criticality index for each candidate is derived based on the information available from failure mode and effects analysis (FMEA) document or warranty data from a prior system. It makes use of this information to develop reliability demonstration test plan for the identified (critical) failure mechanisms and physical elements. It also highlights the benefits of using prior information in order to locate critical spots in the design and in subsequent development of test plans. A case example is presented to demonstrate the proposed approach.

Novel Approach for Determining Spots of Critical Lightning Performance Along Transmission Lines

A novel approach is proposed for determining critical spots along transmission lines, concerning lightning performance. It takes into account two localized factors: stroke density and response of line structures to lightning currents. The methodology employs data supplied by lightning location systems and also information about line parameters in order to rank, by means of a severity index, the specific towers along line, which deserve protective actions. The procedure was applied to a real 230 kV line. The results, in terms of first ranked towers, were compared to the history of line outages, as indicated by a fault locator. The results were in very good agreement. This denotes the potential of the proposed approach for general application.

Fatigue Strength and Evaluation of Double-Mast Arm Cantilevered Sign Structures

Double-mast arm cantilevered sign structures are widely used in Indiana and in many other states. Because of the large sign area and relatively high flexibility, wind loading on these sign structures occasionally produces significant stress cycles. Cracking caused by fatigue damage may occur at several critical spots on the sign structures. An analytical investigation of the fatigue lives of the critical details in double-mast arm sign structures is discussed in this paper. An analytical procedure is introduced, and wind load selection and simulation are explained. Finite element models based on a prototype double-mast arm sign structure are described, and dynamic analyses and fatigue life results are presented. It was found that the post-to-base plate socket weld connection was the most critical detail and that variations in the fatigue life occurred because of differences in the wind environment at various sites.

Fatigue Strength and Evaluation of Double–Mast Arm Cantilevered Sign Structures

Double–mast arm cantilevered sign structures are widely used in Indiana and in many other states. Because of the large sign area and relatively high flexibility, wind loading on these sign structures occasionally produces significant stress cycles. Cracking caused by fatigue damage may occur at several critical spots on the sign structures. An analytical investigation of the fatigue lives of the critical details in double–mast arm sign structures is discussed in this paper. An analytical procedure is introduced, and wind load selection and simulation are explained. Finite element models based on a prototype double–mast arm sign structure are described, and dynamic analyses and fatigue life results are presented. It was found that the post-to–base plate socket weld connection was the most critical detail and that variations in the fatigue life occurred because of differences in the wind environment at various sites.

Microscopic analysis for water stressed by high electric fields in the prebreakdown regime

Analysis of the electrical double layer at the electrode-water interface for voltages close to the breakdown point has been carried out based on a static, Monte Carlo approach. It is shown that strong dipole realignment, ion-ion correlation, and finite-size effects can greatly modify the electric fields and local permittivity (hence, leading to optical structure) at the electrode interface. Dramatic enhancements of Schottky injection, providing a source for electronic controlled breakdown, are possible. It is also shown that large pressures associated with the Maxwell stress tensor would be created at the electrode boundaries. Our results depend on the ionic density, and are in keeping with recent observations. A simple, perturbative analysis shows that high field regions with a sharp variation in permittivity can potentially be critical spots for instability initiation. This suggests that the use of polished electrodes, or composite materials, or alternative nonpolar liquids might help enhance high-voltage operation.

Investigations on a statistical measure of the non-proportionality of stresses

In mechanical engineering fatigue assessment of components, where complex non-proportional loads are acting on, plays an important role to identify critical spots and to predict the lifetime till crack initiation. For this case, a measure for the complexity of local stress states would be very useful to select appropriate criteria or fatigue life calculation methods. In this contribution, a degree of non-proportionality of stresses is investigated, which has been originally proposed by Chu et al. This degree of non-proportionality of stresses is a statistical measure for the variation of principal stress directions. It is shown, how this parameter can be determined for general triaxial stress states, and conditions are derived for mathematical consistency. An example shows that the degree of non-proportionality of stresses can be used even for the compensation of methodical weaknesses of the critical plane criterion, when assessing fatigue effects of local rotating principal stresses for ductile materials such as tempered steel. The critical plane criterion has been used in conjunction with a stress based method (concept of synthetic S/ N-curves, which is quite popular in Germany) and linear damage accumulation according Miner’s rule.

Experimental Investigations of Foaming in a Packed Tower for Sour Water Stripping

A foaming problem in an industrial-size deacidifier (packed column) within the ammonia−hydrogen sulfide circulation scrubbing process (AS process) on a specific site is experimentally investigated. The foamability of solutions is successfully assessed in a small test cell, and the Bikermann coefficient is calculated to characterize the foaminess behavior. The investigations revealed that filtration of the real sour water taken from the specific site does not alter foaming characteristics. Impurities, especially phenol and its derivatives, cresols, are found to highly contribute to foaminess behavior. Experiments in a pilot plant revealed higher pressure drop and lower flood point data. Critical spots of foam formation are identified, and design suggestions for column internals are given.

A Simulation Tool to Analyse the TETRA Transceiver Performance in Adverse Propagation Conditions

With growing demand for digital wireless communica tion systems, simulation tools are increasingly impor tant as means for fast, accurate prediction of system performance. The development of a software simula tion tool to analyse the performance of emerging stan dard Trans European Trunked Radio is described. It estimates the average Bit Error Rate of the communi cation link in a variety of propagation conditions, while incorporating different component subsystems in the chain. The modelling process of various components of the transceiver chain and the propagation channel is discussed; the resulting implementation is demon strated. To show the tool's use, the BER performance of TETRA with post-detection diversity under several propagation conditions has been evaluated, with an improvement in the range of 5 to 11.5 dB. System per formance is reported under Simulcast conditions, a transmission strategy that enables coverage of large, low-traffic areas. A model is incorporated using a novel approach that considers the effect of the multipath channel. A significant increase of the expected error floor is anticipated for normal operating conditions. Finally, the RMS simulcast channel delay spread was identified as a suitable parameter to characterise the most critical spots of the area covered.

Experimental and Numerical Studies on Performance of Passive Decay Heat Removal by a Water Cooling Panel from a High-Temperature Gas-Cooled Reactor

An experiment was carried out to simulate passive decay heat removal from a high-temperature gas-cooled reactor based on water cooling panel system. The experiment is aimed at investigating the temperature distribution of the system and the effectiveness of decay heat removal. The experimental apparatus consists of a pressure vessel of 1 m in diameter and 3 m in height, bristling with nineteen stand pipes atop and containing internal heaters with a maximum heating rate of 100 kW to simulate the decay heat of the core. The pressure vessel is surrounded by the water cooling panels in an air-filled cavity, which resembles the actual reactor installation. The computational code THANPACST2 was benchmarked by the experimental data to verify its numerical methods including a newly-proposed axi-symmetrical model of the three-dimensional structures of the stand pipes by porous body cells. Under the conditions of helium gas pressure of 0.47 MPa and temperatures up to 430°C in the pressure vessel, the temperatures of the critical spots near the top of the pressure vessel, where peak temperatures appeared, were estimated within discrepancies between −25 and +70°C from the experimental data. The heat transferred to the cooling panel was estimated to be 4.1% less than the experimental value.

High-intensity ultrasonic spectra in water and brain tissue

A common method of brain tumour surgery is using CUSA (cavitation ultrasonic surgical aspirator). While using CUSA, there is a strong focusing of the ultrasonic field within the cranium. This can cause damage to healthy brain tissue. Therefore, the ultrasonic field intensity at the critical spots must be measured. These measurements cannot be made in vivo, thus raising the need for a substitute model. In this paper, frequency spectra of the CUSA probe was measured at its working frequency of 25 kHz in an oval container (simulating the cranium). The measurement was made at few field intensities, K hydrophone in the container, and the B&K microphone outside it. The medium temperature has been controlled. Calf brain tissue, physiologically similar to human, was used as a substitute model. The same measurement was repeated in water to examine the spectrum difference in high- and low-attenuation media. During the measurement, the occurrence of the cavitation was observed by spectra changes.