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© 2019 Techno-Press, Ltd. In this study the spatial variability of soils is substantiated physically and numerically by using random field theory. Heterogeneous samples are fabricated by combining nine homogeneous soil clusters that are assumed to be elements of an adopted random field. Homogeneous soils are prepared by mixing different percentages of kaolin and bentonite at water contents equivalent to their respective liquid limits. Comprehensive characteristic laboratory tests were carried out before embarking on direct shear experiments to deduce the basic correlations and properties of nine homogeneous soil clusters that serve to reconstitute the heterogeneous samples. The tests consist of Atterberg limits, and Oedometric and unconfined compression tests. The undrained shear strength of nine soil clusters were measured by the unconfined compression test data, and then correlations were made between the water content and the strength and stiffness of soil samples with different consistency limits. The direct shear strength of heterogeneous samples of different stochastic properties was then evaluated by physical and numerical modelling using FISH code programming in finite difference software of FLAC 3D . The results of the experimental and stochastic numerical analyses were then compared. The deviation of numerical simulations from direct shear load-displacement profiles taken from different sources were discussed, potential sources of error was introduced and elaborated. This study was primarily to explain the mathematical and physical procedures of sample preparation in stochastic soil mechanics. It can be extended to different problems and applications in geotechnical engineering discipline to take in to account the variability of strength and deformation parameters.

In project planning process, resource over-allocation is a major shortcoming. The resource over-allocation causes the schedules not to be applicable in practice. Besides, in real projects, it is hard to predict the duration of activities since they may be changed due to lack of resources, delays in delivering resources, improper workers etc. that cause activities not to complete as predicted. Hence, it is important to develop a method that can schedule activities by considering different execution conditions. In this research, we focused on another aspect of solving resource over-allocation problem by considering uncertain activity duration. For this purpose, a mixed integer programming model is developed where the objective function is maximizing net present value of the project while duration of activities are not deterministic. Then a number of examples are solved using a heuristic algorithm. The results showed that the proposed algorithm can effectively solve the case studies with no over-allocated resources. Afterward, the algorithm is solved using the data of constructing a hospital. The results showed that the algorithm can successfully use for real projects.

Purpose: To assess the outcomes of the insertion of the MyoRing (DIOPTEX, GMBH, Linz, Austria) by applying the Femtosecond Laser Technology (FLT) method in eyes that have keratoconus problem. Methods: A prospective, nonrandomized, clinical examination was managed. 27 eyes of 15 subjects with stable keratoconus (6 females and 9 males), with lifetimes differing from 14 to 49 years were involved. All subjects have problems about decreased fine-accurate ocular awareness, lens intolerantness or trouble, and also the middle corneal height larger than 350 micrometers. MyoRing additions of about 320 micrometers into height and 2.5 mm into radius were inserted in each subject inside an Intrastromal Corneal Pocket using(ICP) formed with applying FLT. Ocular, refractive errors, corneal shape, and pachymetry changes were assessed throughout a 6-months follow-up period. Results: The average UDVA (uncorrected distance visual acuity) notably increased originating at 1.73 ± 0.53 LogMAR preoperationally to 0.54 ± 0.40 LogMAR post-operationally. The average CDVA (corrected distance ocular awareness) notably increased from 0.59 ± 0.47 LogMAR preoperationally to 0.27 ± 0.16 LogMAR post-operationally. The change in the average UDVA and CDVA was analytically meaningful (P< 0.000). The average reduction in the average keratometry from preoperational to 26 weeks post operational was -6.41 ± 3.62 D. This change was analytically meaningful (P< 0.000). The average lowest and highest keratometry amounts were similarly analytically notable at shorter than 26 weeks preoperatively. A notable increase in UDVA and CDVA was observed 26 weeks following the operation, that was compatible with the notable decrease in sphere and cylinder. Moreover, a notable corneal straightening with an average amount of -6.41 ± 3.62 diopters (D) was determined. Conclusion: MyoRing implantation employing FLT would be a harmless, effective, and predictable method to treat selected subjects of keratoconus, being a helpful choice for the therapy of keratoconus.

Purpose: To assess the visual and refractive outcomes of flexible toric iris claw phakic intraocular lens implantation for correction of moderate to high myopia with astigmatism. Methods: In this non-randomized prospective study, 31 eyes of 18 patients including 8 male and 10 female subjects with mean age of 27.62±5.53 (range 19 to 38) years with moderate to high myopia and astigmatism underwent toric Artiflex (Ophtec BV, Groningen, Netherlands) phakic intraocular lens (PIOL) implantation. Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) were measured in logarithm of minimum angle of resolution (logMAR) notations. Manifest refraction, safety, efficacy, predictability and complications were measured 6 months after surgery. Results: Pre-operatively, mean spherical equivalent (SE) refractive error was -9.68±1.92 (range -14.00 to -6.00) diopter (D) and mean cylinder was -2.79±1.06 (range -4.75 to -1.00) D. After a minimum of 6 months, mean SE was -0.38±0.27 (range -0.87 to 0.00) D and mean cylinder was -0.66±0.43 (range -1.50 to 0.00) D. SE was within 0.50 D of emmetropia in 63.8% and within 1.0 D of target refraction in 100% of eyes. UDVA was equal or better than 20/20 in 45.1% of eyes while CDVA was equal or better than 20/20 in 67.7%; 83.8% of eyes gained 1 or more Snellen lines of CDVA after surgery. No serious complications occurred in this series of cases. Conclusions: Implantation of the toric Artiflex PIOL is a safe and effective procedure for correction of moderate to high myopia with astigmatism.

Background: Refractive eye are the most common people eye complaints and there are different ways to refractive correction. In this study we compare the effect of two phakic intraocular lenses, Artiflex versus Implantable Contact Lens (ICL). Methods: In a prospective clinical trial study, 40 eyes of 20 patients who came to ophthalmology clinic to correct their refractive error were examined. In 20 eyes artiflex was inserted randomly and in the other 20 eyes, ICL was inserted. After 6 months uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), contrast sensitivity, intraocular pressure (IOP), specular microscopy and anterior uveitis was assessed in both groups. Finding: In this study, there is no statistical difference between UCVA, BCVA, IOP, cataract incidence, contrast sensitivity, specular microscopy 6 months after surgery in both groups. 40% of eyes in Artiflex group developed anterior chamber reaction 6 months post-operatively but no patient in ICL group. So there is obvious difference in the rate of anterior chamber reaction between these two groups. Conclusion: These two lenses have similar outcomes except in the incidence rate of anterior chamber reaction that is greater in the artiflex group. So these two lenses are safe with predictable outcome in treating high myopia.

Purpose To report the efficacy, safety, predictability and complications of photorefractive keratectomy (PRK) with intraoperative application of mitomycin-C (MMC). Methods This historical cohort study was performed on 1,250 eyes of 625 patients who underwent PRK using the Technolas 217 excimer laser machine by a single surgeon with intraoperative use of MMC 0.02% up to 2 minutes, depending on depth of ablation. A complete ophthalmologic examination was performed which included refraction uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA) and slitlamp biomicroscopy. Outcomes were analyzed after one year of follow-up. Results The mean preoperative spherical equivalent refractive error was −4.85±2.27 (range, −2.50 to −13.5) diopters (D). Mean depth of ablation was 89±22 microns and mean time to reepithelialization was 4.5±1.7 days. At final follow-up, UCVA of 20/20 and 20/40 or more was achieved in 92.1% and 99.2% of eyes, respectively. One year postoperatively, 69.4% and 91% of eyes were within ±0.50 D and ±1.00 D of emmetropia.Overall, 62 eyes (4.9%) developed one or two lines of decrease in BCVA, and 50 eyes (4%) developed corneal haze which was grade 1 or 2 in most cases; grade 3 and 4 corneal haze was found in 4 and 2 eyes, respectively. No other adverse event was noted during the study period. Conclusion PRK with intraoperative application of MMC provides excellent visual outcomes with acceptable safety and predictability, and entails minimal side effects.