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Silverman D.T.,U.S. National Cancer Institute | Samanic C.M.,U.S. National Cancer Institute | Lubin J.H.,U.S. National Cancer Institute | Blair A.E.,U.S. National Cancer Institute | And 12 more authors.
Journal of the National Cancer Institute | Year: 2012

Background Most studies of the association between diesel exhaust exposure and lung cancer suggest a modest, but consistent, increased risk. However, to our knowledge, no study to date has had quantitative data on historical diesel exposure coupled with adequate sample size to evaluate the exposure-response relationship between diesel exhaust and lung cancer. Our purpose was to evaluate the relationship between quantitative estimates of exposure to diesel exhaust and lung cancer mortality after adjustment for smoking and other potential confounders.MethodsWe conducted a nested case-control study in a cohort of 12315 workers in eight non-metal mining facilities, which included 198 lung cancer deaths and 562 incidence density-sampled control subjects. For each case subject, we selected up to four control subjects, individually matched on mining facility, sex, race/ethnicity, and birth year (within 5 years), from all workers who were alive before the day the case subject died. We estimated diesel exhaust exposure, represented by respirable elemental carbon (REC), by job and year, for each subject, based on an extensive retrospective exposure assessment at each mining facility. We conducted both categorical and continuous regression analyses adjusted for cigarette smoking and other potential confounding variables (eg, history of employment in high-risk occupations for lung cancer and a history of respiratory disease) to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death (case subjects)/reference date (control subjects). All statistical tests were two-sided.ResultsWe observed statistically significant increasing trends in lung cancer risk with increasing cumulative REC and average REC intensity. Cumulative REC, lagged 15 years, yielded a statistically significant positive gradient in lung cancer risk overall (P trend = .001); among heavily exposed workers (ie, above the median of the top quartile [REC ≥ 1005 μg/m 3-y]), risk was approximately three times greater (OR = 3.20, 95% CI = 1.33 to 7.69) than that among workers in the lowest quartile of exposure. Among never smokers, odd ratios were 1.0, 1.47 (95% CI = 0.29 to 7.50), and 7.30 (95% CI = 1.46 to 36.57) for workers with 15-year lagged cumulative REC tertiles of less than 8, 8 to less than 304, and 304 μg/m 3-y or more, respectively. We also observed an interaction between smoking and 15-year lagged cumulative REC (P interaction = .086) such that the effect of each of these exposures was attenuated in the presence of high levels of the other.ConclusionOur findings provide further evidence that diesel exhaust exposure may cause lung cancer in humans and may represent a potential public health burden. © 2012 The Author.


Attfield M.D.,ERS Inc | Schleiff P.L.,U.S. National Institute for Occupational Safety and Health | Schleiff P.L.,Stewart Exposure Assessments LLC | Lubin J.H.,U.S. National Cancer Institute | And 6 more authors.
Journal of the National Cancer Institute | Year: 2012

Background Current information points to an association between diesel exhaust exposure and lung cancer and other mortality outcomes, but uncertainties remain.MethodsWe undertook a cohort mortality study of 12315 workers exposed to diesel exhaust at eight US non-metal mining facilities. Historical measurements and surrogate exposure data, along with study industrial hygiene measurements, were used to derive retrospective quantitative estimates of respirable elemental carbon (REC) exposure for each worker. Standardized mortality ratios and internally adjusted Cox proportional hazard models were used to evaluate REC exposure-associated risk. Analyses were both unlagged and lagged to exclude recent exposure such as that occurring in the 15 years directly before the date of death.ResultsStandardized mortality ratios for lung cancer (1.26, 95% confidence interval [CI] = 1.09 to 1.44), esophageal cancer (1.83, 95% CI = 1.16 to 2.75), and pneumoconiosis (12.20, 95% CI = 6.82 to 20.12) were elevated in the complete cohort compared with state-based mortality rates, but all-cause, bladder cancer, heart disease, and chronic obstructive pulmonary disease mortality were not. Differences in risk by worker location (ever-underground vs surface only) initially obscured a positive diesel exhaust exposure-response relationship with lung cancer in the complete cohort, although it became apparent after adjustment for worker location. The hazard ratios (HRs) for lung cancer mortality increased with increasing 15-year lagged cumulative REC exposure for ever-underground workers with 5 or more years of tenure to a maximum in the 640 to less than 1280 μg/m 3-y category compared with the reference category (0 to <20 μg/m 3-y; 30 deaths compared with eight deaths of the total of 93; HR = 5.01, 95% CI = 1.97 to 12.76) but declined at higher exposures. Average REC intensity hazard ratios rose to a plateau around 32 μg/m 3. Elevated hazard ratios and evidence of exposure-response were also seen for surface workers. The association between diesel exhaust exposure and lung cancer risk remained after inclusion of other work-related potentially confounding exposures in the models and were robust to alternative approaches to exposure derivation.ConclusionsThe study findings provide further evidence that exposure to diesel exhaust increases risk of mortality from lung cancer and have important public health implications. © 2012 The Author.


Suhir E.,Bell Laboratories | Suhir E.,Vienna University of Technology | Suhir E.,Ariel University | Suhir E.,ERS Co.
Modern Physics Letters B | Year: 2013

A simple physically meaningful predictive model is developed for the assessment of the acceptable duration of the repair (restoration) time to keep the system's availability level sufficiently high. The role of the random nature of the restoration time is taken into account. High availability can be achieved by making large, after a malfunction is detected, the ratio of the intensity of restorations to the failure rate. It is shown how this way to go could be effectively quantified. The general concept is illustrated by a numerical example. © World Scientific Publishing Company.


Suhir E.,Bell Laboratories | Suhir E.,University of California at Santa Cruz | Suhir E.,University of Maryland University College | Suhir E.,ERS Co. LLC
ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik | Year: 2011

Application of mechanical pre-stressing could be an effective means for achieving a failure-mode-shift-free "destructive ALT effect" in electronic and photonic devices and micro-electro-mechanical systems (MEMS). A simple, physically meaningful and easy-to-use analytical ("mathematical") predictive model has been developed to assess the magnitude and the distribution of stresses in a bi-material assembly subjected to the combined action of thermally induced (considered by the ALT design) and external ("mechanical") pre-stressing. Such a compressive pre-stressing is applied to the assembly component that is expected to experience thermal compression. The model is an extension and a modification of the author's 1986 and 1989 "bi-metal thermostat" models suggested as a generalization of the 1925 Timoshenko's theory. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Suhir E.,Bell Laboratories | Suhir E.,University of California at Santa Cruz | Suhir E.,ERS Co. LLC
Modern Physics Letters B | Year: 2013

The published work on analytical («mathematical») and computer-aided, primarily finite-element-analysis (FEA) based, predictive modeling of the dynamic response of electronic systems to shocks and vibrations is reviewed. While understanding the physics of and the ability to predict the response of an electronic structure to dynamic loading has been always of significant importance in military, avionic, aeronautic, automotive and maritime electronics, during the last decade this problem has become especially important also in commercial, and, particularly, in portable electronics in connection with accelerated testing of various surface mount technology (SMT) systems on the board level. The emphasis of the review is on the nonlinear shock-excited vibrations of flexible printed circuit boards (PCBs) experiencing shock loading applied to their support contours during drop tests. At the end of the review we provide, as a suitable and useful illustration, the exact solution to a highly nonlinear problem of the dynamic response of a «flexible-and-heavy» PCB to an impact load applied to its support contour during drop testing. © 2013 World Scientific Publishing Company.


Suhir E.,University of California at Santa Cruz | Suhir E.,Vienna University of Technology | Suhir E.,ERS Co. LLC
Microelectronics Reliability | Year: 2013

Application of the consistent, comprehensive and physically meaningful probabilistic design for reliability (PDfR) concept can not only help to understand the physics-of-failure of an electronic product, but, most importantly, can enable one to predict, quantify and assure its failure-free performance in the field. The use of the PDfR concept can be helpful also in the development and implementation of the new generation of the most feasible and effective qualification test (QT) methodologies, practices and specifications. The major ten PDfR requirements ("commandments") for the predicted, quantified and assured reliability of an electronic or a photonic product could be formulated as follows: (1) PDfR approach is an effective means for improving the state-of-the-art in the field, having in mind that nothing is perfect, and that the difference between an unreliable product and a robust one is "merely" in the level of the never-zero probability of failure (PoF). (2) The best electronic product is, in effect, the best compromise between the needs for its reliability, cost effectiveness and time-to-market (completion) for a particular product and application. (3) Reliability cannot be low, need not be higher than necessary, but, for a cost-effective and a timely product, has to be adequate for a particular product and application. (4) When reliability is imperative, ability to quantify it is a must, especially if optimization is considered: no optimization is possible, of course, if the product's reliability characteristics of interest are not quantified. (5) One cannot design a product with predicted, quantified, optimized and assured reliability by limiting the effort to the highly accelerated life testing (HALT): HALT can test the reliability limits and perhaps to ruggedize the product, but does not quantify reliability. (6) Reliability is conceived at the design stage and should be taken care of, first of all, at this stage, when a "genetically healthy" product is supposed to be created; if the reliability of the product is taken care at this stage, then the subsequent fabrication, qualification and prognostics-and-health-monitoring (PHM) stages will have much better chances to succeed. (7) Reliability evaluations and assurances cannot be delayed until the product is fabricated and shipped to the customer, i.e., cannot be left to the PHM stage: it is too late at this stage to change the design or the materials for improved reliability; that is why, when high reliability is critical (e.g., in the aerospace and military electronics), users have to re-qualify devices to assess their (remaining) useful lifetime (RUL) and to use redundancy in an attempt to build a reliable system out of insufficiently reliable components. (8) Design, fabrication, testing, qualification and PHM efforts should consider, and be specific for, particular products and their most likely actual or at least anticipated applications. (9) Highly cost-effective and highly focused failure oriented accelerated testing (FOAT) geared to a particular pre-determined relevant reliability model and aimed at understanding the physics of failure anticipated by this model is an important constituent part of the PDfR concept and effort. (10) Effective, easy-to-use and physically meaningful predictive modeling (PM) is another important constituent of the PDfR approach; in combination with FOAT, it is a powerful means to carry out meaningful sensitivity analyses (SA), so that the operational reliability of the product is effectively predicted, quantified and assured ("principle of practical confidence"). Analytical ("mathematical") modeling occupies a special place in the modeling effort, because of its compactness and explicit indication on "what affects what" and what could possibly be done to improve the product's performance. In the write-up that follows the above requirements ("commandments") are addressed and discussed in detail. © 2013 Elsevier Ltd. All rights reserved.


Suhir E.,University of California at Santa Cruz | Suhir E.,Vienna University of Technology | Suhir E.,ERS Company LLC | Kang S.-M.,Korea Advanced Institute of Science and Technology
Modern Physics Letters B | Year: 2013

Boltzmann-Arrhenius-Zhurkov (BAZ) model enables one to obtain a simple, easy-to-use and physically meaningful formula for the evaluation of the probability of failure (PoF) of a material after the given time in operation at the given temperature and under the given stress (not necessarily mechanical). It is shown that the material degradation (aging, damage accumulation, flaw propagation, etc.) can be viewed, when BAZ model is considered, as a Markovian process, and that the BAZ model can be obtained as the steady-state solution to the Fokker-Planck equation in the theory of Markovian processes. It is shown also that the BAZ model addresses the worst and a reasonably conservative situation, when the highest PoF is expected. It is suggested therefore that the transient period preceding the condition addressed by the steady-state BAZ model need not be accounted for in engineering evaluations. However, when there is an interest in understanding the physics of the transient degradation process, the obtained solution to the Fokker-Planck equation can be used for this purpose. © 2013 World Scientific Publishing Company.


Suhir E.,Portland State University | Suhir E.,ERS Co.
Journal of Materials Science: Materials in Electronics | Year: 2016

It is shown, based on the developed analytical predictive model, that a significant thermal stress relief can be achieved in an optimized design of an inhomogeneously bonded bi-material assembly, if its bonding system is designed in such a way that the interfacial shearing stress at the ends of the high-modulus-and-high-bonding-temperature mid-portion of the assembly at its boundary with the low-modulus-and-low-bonding-temperature peripheral portion is made equal to the stress at the assembly ends. The numerical example carried out for such an optimized ball-grid-array (BGA) or a column-grid-array (CGA) electronic assembly indicates that the above measure enables one to design an assembly, in which the induced interfacial stresses are about half of the stresses in a regular, non-optimized, but still inhomogeneously bonded assembly with a low-modulus-and/or-low-bonding-temperature material at its ends. The predicted maximum stress in an optimized assembly is only about 41 % of the maximum stress in a homogeneously bonded BGA assembly and about 46 % of the maximum stress in a homogeneously bonded CGA assembly. The numerical data indicated also that the application of the CGA technology in a non-optimized inhomogeneously bonded assembly enables one to achieve a 19 % stress relief in the case of an application of the epoxy adhesive at the peripheral portions of the assembly, and that a 34 % stress relief could be expected in the case of the use of a low modulus solder at the assembly ends. When a BGA technology is considered, the application of an epoxy or a low modulus solder at the peripheral portions of the assembly leads to approximately the same stress relief effect: about 14 % in the case of an epoxy adhesive and about 13 % in the case of a low modulus solder. When a CGA technology is considered, the application of an epoxy at the peripheral portions of the non-optimized assembly leads to about 9.0 % stress relief, while the application of a low modulus solder results in about 24 % stress relief. If, e.g., the yield stress in shear is 1.85 kg/mm2 for the solder in the assembly’s mid-portion and 1.35 kg/mm2 for the peripheral solder material, the application of the CGA technology in combination with an inhomogeneous bond with an epoxy adhesive or a low modulus solder at the assembly ends might enable one to avoid inelastic strains in the solder, weather in the mid-portion or in the peripheral portion, thereby increasing dramatically the fatigue lifetime of the bond. It is even easier to achieve this goal with the use of the suggested optimized design of an inhomogeneous bond. © 2016 Springer Science+Business Media New York


Suhir E.,Portland State University | Suhir E.,ERS Co.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

An updated version of the paper with revised references has been published The review part of the paper addresses analytical (mathematical) modeling in structural analysis in fiber optics engineering, mostly fiber optics interconnects, and deals with optical fibers subjected to thermal and/or mechanical loading (stresses) in bending, tension, compression, or to the combinations of such loadings. Attributes and significance of predictive modeling are indicated and discussed. The review is based mostly on the author’s research conducted at Bell Laboratories, Physical Sciences and Engineering Research Division, Murray Hill, NJ, USA, during his tenure with this company, and, to a lesser extent, on his recent work in the field. The addressed structures include, but are not limited to, optical fibers of finite length: bare fibers; jacketed and dual-coated fibers; fibers experiencing thermal loading; fibers soldered into ferrules or adhesively bonded into capillaries; as well as the roles of geometric and material non-linearity; dynamic response to shocks and vibrations; and possible applications of nano-materials in new generations of coating and cladding systems. The extension part is concerned with a novel, fruitful and challenging directionprobabilistic design for reliability (PDfR) of opto-electronic and photonic products, including optical fibers and interconnects. The rationale behind the PDfR concept is that there is no such thing as zero probability of failure, that the difference between a highly reliable product and an insufficiently reliable product is "merelya" in the level of the never zero probability of its failure and that when the operational performance of the product is imperative, the ability to predict, quantify, assure and, if possible and appropriate, even specify its reliability is highly desirable. Accordingly, the objective of the PDfR effort is to quantify the likelihood of an operational failure of a material, device or a system, including the field of fiber optics. © 2015 SPIE.


Suhir E.,Portland State University | Suhir E.,ERS Co.
Annual IEEE Semiconductor Thermal Measurement and Management Symposium | Year: 2015

Physically meaningful and easy-to-use analytical solutions are obtained, using analytical modeling and theory-of-elasticity approach, for thermal stresses in typical through-silicon-via (TSV) packages of 3D IC devices. The case when the package is heated up from the room temperature to an elevated temperature is considered. Two extreme cases of the TSV geometry are addressed: disc-like vias, with height/thickness-to-diameter ratio is below 0.25, when plane-stress approximation in the 2D elasticity theory can be used, and rodlike vias, with height-to-diameter ratios above 2.5, when plane strain approximation is applicable. The following objectives have been pursued in the analysis: 1) evaluation of the elastic stability of a disc-like via subjected to the thermal «hoop» pressure caused by the thermal expansion mismatch of the copper (Cu) and silicon (Si) materials; 2) assessment of the thermally induced circumferential stresses in the Si wafer; and 3) the evaluation of the expected relief in the longitudinal (in the TSV axial direction) interfacial shearing stresses due to the application of a «surrogate» buffering material, i.e., a material not needed from the standpoint of the functional performance of the design. While the pressure at the Cu/Si interface determines the reliability of the Si material, the longitudinal interfacial shearing stress is critical from the standpoint of the adhesive and cohesive strength of the TSV structure. The numerical example is carried out for different radii of the opening in Si and for the case when Indium is considered as a suitable buffering material. The calculated data indicate that larger openings in Si result in lower pressures on Si and in lower longitudinal interfacial shearing stresses, especially if disc-like vias are employed. The computed data indicate particularly that a 1 μm thick layer of Indium resultes in about 39% reduction in the induced pressure at the Cu/Si boundary for a disc-like TSV and by about 14% - for a rod-like via. As to the longitudinal interfacial shearing stress, the reductions are even greater: about 69% - for a disc-like TSV and about 41% for a rod-like via. Thus, there seems to be an incentive for employing disc-like TSV designs for lower thermal stresses. In the absence of the strain buffer, the pressure in the disc-like TSV design was only about 58% of the pressure in the rod-like via, and the maximum value of the longitudinal shearing stress was about half the stress in the rod-like TSV. The «bad news» is, however, that while the elastic stability of a rod-like via is never a problem, a disc-like via might buckle under the action of the thermally induced «hoop» stresses, and therefore the elastic stability of a disc-like via should always be evaluated and assured. Our analysis starts, for this reason, with the evaluation of the critical (Euler) pressure for a disc-like TSV. © 2015 IEEE.

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