Traffic modeling for telecommunications networks

As new communications services evolve, professionals must create better models to predict system performance. The article provides an overview of computer simulation modelling for communication networks, as well as some important related modelling issues. It gives an overview of discrete event simulation and singles out two important modelling issues that are germane to extant and emerging networks: traffic modelling and rare event simulation. Monte Carlo computer simulation is used as a performance prediction tool and Markov models are considered     

Algorithmic modeling of TES processes

TES (transform-expand-sample) is a versatile class of stationary stochastic processes which can model arbitrary marginals, a wide variety of autocorrelation functions, and a broad range of sample path behaviors. TES parameters are of two kinds: the first kind is used for the exact fitting of the empirical distribution (histogram), while the second kind is used for approximating the empirical autocorrelation function. Parameters of the first kind are easy to determine algorithmically, but those of the second kind require a hard heuristic search on a large parametric function space. This paper describes an algorithmic procedure which can replace the heuristic search, thereby largely automating TES modeling. The algorithm is cast in nonlinear programming setting with the objective of minimizing a weighted sum of squared differences between the empirical autocorrelations and their candidate TES model counterparts. It combines a brute-forte search with steepest-descent nonlinear programming using Zoutendijk's feasible direction method. Finally, we illustrate the efficacy of our approach via three examples: two from the domain of VBR (variable bit rate) compressed video and one representing results from a laser intensity experiment     

Optic nerve compression by carotid arteries in low-tension glaucoma

Low-tension glaucoma (LTG) is manifested by glaucomatous optic nerve damage and visual field loss despite normal intraocular pressure (IOP). We describe 62 patients with classical signs of LTG. Computed tomography (CT) was performed in all patients. In 56 of the patients (90.3%), pathology of the intracavernous carotid arteries adjacent to the intracranial opening of the optic canal could be demonstrated. In 28 patients (45.2%) a clear asymmetry of the optic nerve cupping was found and could be correlated with the severity of the carotid artery pathology. A control group of 24 age-matched patients included five (20.8%) with intracavernous carotid artery calcification and only one (4.2%) with intracavernous ectasia. We suggest that calcification, dilatation and ectasia of the carotid artery into the optic canal may play an important role in the pathogenesis of many cases of LTG. The close proximity of the carotid artery to the optic nerve at this location may result in compressive neuropathy with subsequent glaucomatous damage of the optic nerve head.     

Usefulness of the protection motivation theory in explaining hearing protection device use among male industrial workers.

The present study examined the usefulness of personal variables: noise annoyance, and components of the protection motivation theory (R. W. Rogers, 1983) along with social-organizational factors in explaining hearing protection device (HPD) use among Israeli manufacturing workers. Participants were 281 men exposed to harmful noise levels for which routine HPD use is required by regulation. In practice, 3 HPD user groups were identified: nonusers (n?=?38), occasional users (n?=?125), and regular users (n?=?118). HPD use was objectively verified. HPD use was primarily related to the personal variables but not to management pressure, coworker pressure, or family support. The most powerful predictors of HPD use were perceived self-efficacy (for long-term HPD use), perceived susceptibility (to hearing loss), and noise annoyance, together explaining 48% of the outcome variance. These findings have implications for interventions aimed at motivating workers to use HPDs regularly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consideration of technological constraints and functional abnormalities in the algorithms of systems for automatically controlling the frequency and power of power units

We describe the results of work on achieving constant high-quality operation of systems for automatically controlling the frequency and power of power units by automatically taking into consideration technological constraints that unavoidably occur during the operation of power-generating equipment and functional abnormalities caused by failures of peripheral devices used in the composition of an automatic process control system.     

"Child health psychology": Erratum.

Reports an error in "Child health psychology" by Dennis Drotar, Suzanne Bennett Johnson, Ron Iannotti, Norman Krasnegor, Karen A. Matthews, Barbara G. Melamed, Sharon Millstein, Rolf A. Peterson, Debbie Popiel and Donald K. Routh (Health Psychology, 1989, Vol 8[6], 781-784). The name of the author, Sharon Millstein, should be Susan Millstein. It appears correctly in this record. (The following abstract of the original article appeared in record 2008-09118-001.) The term child health psychology refers to the field of research on the behavioral aspects of children's health and illness. At this time we need to continue the work of the child health psychology special interest group and to draw into the Division of Health Psychology a much larger number of developmental psychologists, who need to be informed about the relevance of their scientific training to child health issues. We call the Division's attention and that of granting agencies such as the National Institute of Child Health and Human Development to the following high-priority child health research issues: adherence to pediatric medical regimens; child health promotion; family influences on child and adolescent health and disease; and stress and coping in childhood illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Change in structure and properties of the weld joints of Cr−Mo−V steel steam pipe in long service

Conclusions 1.The structure, mechanical properties, high-temperature strength, and tendency toward brittle fracture of the weld joints in 12Kh1MF steel remain quite stable during service at 565\dgC for 120,000h.Additional thermal diffusion aging at the same temperature for 80,000 h does not lead to a significant change in structure and properties. li]2.|With a service time exceeding 250,000 h displacement of the high-temperature branch of the logarithmic decrement of damping \gd into the area of operating temperatures (545\2-565\dgC) may be expected. li]3.|The results obtained may be used in determination of the life of steam pipe weld joints.F. É. Dzerzhinskii All-Union Scientific-Research Institute for Thermal Engineering. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 46–49, May, 1986.     

Child health psychology.

[Correction Notice: An erratum for this article was reported in Vol 9(6) of Health Psychology (see record 2008-09119-001). The name of the author, Sharon Millstein, should be Susan Millstein.] The term child health psychology refers to the field of research on the behavioral aspects of children's health and illness. At this time we need to continue the work of the child health psychology special interest group and to draw into the Division of Health Psychology a much larger number of developmental psychologists, who need to be informed about the relevance of their scientific training to child health issues. We call the Division's attention and that of granting agencies such as the National Institute of Child Health and Human Development to the following high-priority child health research issues: adherence to pediatric medical regimens; child health promotion; family influences on child and adolescent health and disease; and stress and coping in childhood illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)