A six-channel microstrip diplexer for multi-service wireless communication systems

In this paper, a six-channel microstrip diplexer is designed and fabricated. It operates at 0.75/0.85/1/1.25/1.6/1.8 GHz for multi-service wireless communication systems. It consists of two stub-loaded resonators, which are integrated by coupled lines. The channels are close together, which makes the proposed diplexer suitable for frequency division duplex (FDD) schemes. The proposed structure has a compact size of 0.025 λg2 where λg is the guided wavelength calculated at 0.75 GHz. The other advantages of the introduced multi-channel diplexer are the low insertion losses of 1.62/1.27/0.43/0.53/1.26 and 1 dB, as well as good return losses of 26/26/25/25/21.7 and 22 dB at 0.75/0.85/1/1.25/1.6/1.8 GHz respectively. A good isolation of less than 22 dB is obtained between the channels. In order to design the presented diplexer a designing technique is used which is based on the proposing of an equivalent approximated LC model and calculating the inductors and capacitors. To confirm the simulation results, the introduced diplexer is fabricated and measured

Two-step versus Single Application of Mitomycin-C in Photorefractive Keratectomy for High Myopia

Purpose: To evaluate the long-term outcomes of two-step versus single application of mitomycin-C (MMC) during photorefractive keratectomy (PRK) for high myopia. Methods: This randomized clinical trial included consecutive patients with high myopia (exceeding 7 D). Patients underwent PRK and were randomized to two methods of MMC 0.02% application as follows: in the single application group, MMC was applied for 45 seconds followed by irrigation; in the two-step group MMC was used identically followed by repeat application for another 15 seconds and corneal surface irrigation. Visual acuity, refractive error, pachymetry, topography, corneal haze and complications were compared between the two groups 18 months after surgery. Results: One hundred and forty patients (70 subjects in either study arm) underwent PRK according to the study protocol. Mean spherical equivalent refractive error was significantly reduced from baseline to -1.16΁0.39 D in the single application group and to -1.07΁0.39 D in the two-step group. Sixteen (11.5%) versus 8 (5.7%) eyes lost one or more line(s) of best corrected visual acuity in the single application group as compared to the two-step group (P=0.05). Corneal haze was observed in 18 (12.9%) and 8 (5.7%) eyes in the single application versus two-step group, respectively (P=0.04). Grade 3 corneal haze was not observed in the two-step group but occurred in five eyes (3.6%) in the single application group (P=0.03). No eyes developed corneal ectasia during the follow-up period. Conclusion: Two-step intraoperative application of MMC 0.02% in highly myopic eyes undergoing PRK can reduce the frequency and severity of haze formation

Robust and Flexible Hydrocarbon Production Forecasting Considering the Heterogeneity Impact for Hydraulically Fractured Wells

Producing oil and gas from increasingly more difficult reservoirs has become an unavoidable challenge for the petroleum industry because the conventional hydrocarbon resources are no longer able to maintain the production levels corresponding to the global energy demand. As the industrial investments in developing lower permeability reservoirs increase and more advanced technologies, such as horizontal drilling and hydraulic fracturing, gain more attention and applicability, the need for more reliable means of production forecasting also become more noticeable. Production forecasting of hydraulically fractured wells is challenging, particularly for heterogeneous reservoirs, where the rock properties vary dramatically over short distances, significantly affecting the performance of the wells. Despite the recent improvements in well performance prediction, the issue of heterogeneity and its effects on well performance have not been thoroughly addressed by the researchers and many aspects of heterogeneity have yet remained unnoticed. In this paper, a novel empirical approach for production forecasting of multi-fractured horizontal wells is presented in an attempt to effectively include the effect of heterogeneity. This approach is based on the integration of hyperpolic decline curve analysis (DCA) and heterogeneity impact factor (HIF). This newly defined ratio quantifies the heterogeneity impact on the hydraulically fractured well performance and is calculated on the basis of net pressure match interpretation and post-fracture well test analysis. The proposed approach of the decline curve using heterogeneity impact factor (DCH) is validated against data from a southern North Sea field. The results show a maximum of 15% difference between the outcome of the proposed method and the most detailed three-dimensional history-matched model, for a 15 year period of production forecasts. DCH is a novel, fast, and flexible method for making reliable well performance predictions for hydraulically fractured wells and can be used in forecasting undrilled wells and the range of possible outcomes caused by the heterogeneity

Fuzzy logic-based algorithm resource scheduling for improving the reliability of cloud computing

Cloud computing is an important infrastructure for distributed systems with the main objective of reducing the use of resources. In a cloud environment, users may face thousands of resources to run each task. However, allocation of resources to tasks by the user is an impossible endeavor. Accurate scheduling of system resources results in their optimal use as well as an increase in the reliability of cloud computing. This study designed a system based on fuzzy logic and followed by an introduction of an efficient and precise algorithm for scheduling resources for improving the reliability of cloud computing. Waiting and turnaround times of the proposed method were compared to those of previous works. In the proposed method, the waiting time is equal to 26.99 and the turnaround time is equal to 82.99. According to the results, the proposed method outperforms other methods in terms of waiting time and turnaround time as well as accuracy

A cost-utility analysis of different antiviral medicine regimens in patients with chronic hepatitis C virus genotype 1 infection

Background: Despite the introduction of new drug regimens with high effectiveness for the hepatitis C virus (HCV) patients, especially in HCV genotype 1, no cost-effectiveness study on the selection of the superior drug strategy in Iran has been conducted yet. Objectives: This study is aimed to assess the cost-effectiveness of the three drug regimens of pegylated interferon and ribavirin (PR), sofosbuvir (SOF) + PR and ledipasvir and sofosbuvir (LDV/SOF) in patients with HCV genotype 1 in Iran in the year 2014. Methods: A Markov micro-simulation model was used to evaluate the cost-effectiveness of the three drug strategies for a cohort of 10000 patients. Quality-adjusted life-years (QALYs) were extracted from published studies. Cost data was estimated through the review of medical records and obtaining experts opinion. Results: The results showed that the SOF + PR drug compared with PR had a lower cost and was more effective, but compared with the LDV/SOF, in spite of its lower cost, it was less efficient. The QALY values obtained for PR, SOF + PR and LDV/SOF, respectively, were 10.98, 12.08 and 12.28 and their costs were $41,741,$ 7,676 and $46,993. Moreover, the results obtained from acceptability curves showed that SOF + PR were the most cost-effective treatment for thresholds below$ 45,270 PPP. Conclusions: The use of SOF + PR regimen or LDV/SOF can significantly reduce the incidence of complications associated with the disease. For example, short and long-term outcomes are better than the current drug regimens for HCV genotype 1 patients in all stages of the disease

Modeling the Risk of Commercial Failure for Hydraulic Fracturing Projects Due to Reservoir Heterogeneity

Hydraulic fracturing technologies play a major role in the global energy supply and affect oil pricing. The current oil price fluctuations within 40 to 55 USD per barrel have caused diminished economical margins for hydraulic fracturing projects. Hence, successful decision making the for execution of hydraulic fracturing projects requires a higher level of integration of technical, commercial, and uncertainty analyses. However, the complexity of hydraulic fracturing modeling, and the sensitivity and the effects of uncertainty of reservoir heterogeneity on well performance renders the integration of such studies rather impractical. The impact of reservoir heterogeneity on hydraulic fracturing performance has been quantified by the introduction of Heterogeneity Impact Factor (HIF) and formulas have been developed to forecast well performance using HIF. These advances provide a platform for introducing a practical approach for introducing the Risk of Commercial Failure (RCF) due to reservoir heterogeneity in hydraulic fracturing projects. This paper defines such a parameter and the methodology to calculate it in a time-efficient manner. The proposed approach has been exercised on a real project in which a RCF of 20% is computed. The analysis also covers the sensitivity on Capital Expenditure (CAPEX), Operational Expenditure (OPEX), gas price, HIF and discount rate

IOLMaster versus Manual Keratometry after Photorefractive Keratectomy

Purpose: To compare keratometric measurements using a Javal type manual keratometer with IOLMaster in eyes undergoing photorefractive keratectomy (PRK) for myopia. Methods: In this comparative case series, we studied patients aged 21 to 27 years scheduled for myopic PRK. Keratometry was performed preoperatively and three months after the procedure using a Javal type manual keratometer and the IOLMaster. We compared postoperative measurements obtained by both instruments with the clinical history method (CHM). Results: Seventy eyes of 35 patients with mean age of 23.45±1.55 years were studied. Mean preoperative spherical equivalent was -4.53±1.3 D. Average preoperative IOLMaster and manual keratometric readings were 45.95±1.23 D and 46.32±1.18 D, respectively. Postoperatively, mean IOLMaster measurements was 38.03±0.68 D and that of manual keratometry was 43.15±1.1 D. Compared to CHM measurements, the 95% limits of agreement were ‑5.95 to -0.85 for the IOLMaster and -1.44 to 4.04 for manual keratometry. Conclusion: Keratometric measurements with the IOLMaster and a Javal type manual device are comparable after PRK; both are largely deviant from the CHM and can yield misleading results