Short-term scheduling of hybrid thermal, pumped-storage, and wind plants using firefly optimization algorithm

This paper presents a novel method based on an enhanced firefly algorithm (EFA) to solve scheduling hybrid thermal, pumped-storage, and wind plants. Since the scheduling problem is inherently discrete, basic EFA and binary encoding/decoding techniques are used in the proposed EFA approach. Optimal power values of thermal and pumped-storage units are determined separately in the presence of uncertainty caused by wind speed. The proposed method is applied to a real plant, including four pumped-storage units, 34 thermal units with different characteristics, and one wind turbine plant. In addition, dynamic constraints of upstream and downstream sources and constraints regarding thermal and wind units are also considered for finding the optimal solution. In addition, the proposed EFA is successfully applied to a real plant, and the results are compared with those of the three available methods. The results show that the proposed method has converted to a more optimal cost than the other methods

Evaluation of bond strength of orthodontic brackets without enamel etching

Background: to compare the shear bond strength of brackets with and without enamel etching. Material and Methods: In this study, 60 sound premolars were randomly divided into four different groups: 1- TXE group: Enamel etching + Transbond XT adhesive + Transbond XT composite. 2- TXS group: Transbond plus self-etch adhesive + Transbond XT composite. 3- PQ1E group: Enamel etching + PQ1 adhesive + Transbond XT composite. 4- PQ1 group: PQ1 adhesive + Transbond XT composite. The shear bond strengths of brackets were evaluated using universal testing machine at cross head speed of 0.5 mm/ min. The Adhesive Remnant Index (ARI) was also measured. One-way ANOVA, Tukey’s post hoc, Kruskal-wallis and Mann-Witney U test were used for data analysis. Results: There was a significant difference between etched and unetched groups respect to SBS and ARI ( P <0.05), however; no significant difference was observed between unetched group and self-etch adhesive group ( P > 0.05). The shear bond strength of PQ1 group was the least but in acceptable range and its ARI was less than other groups. Conclusions: PQ1 adhesive can be used for bracket bonding without enamel etching with adequate bond strength and minimal ARI

An empirical study to measure the relationship between management style and conflict management

Leadership plays an important role among five main components of management. These days, many organizations try to resolve any existing conflicts through adapting an appropriate leadership strategy. During the past few years, there are increasing interests in examining the relationship between management style and conflict management. The proposed study of this paper performs an empirical study to find the relationship between relationship-oriented leadership style and solution-oriented strategy as well as between leadership style and conflict management. The proposed study distributed a questionnaire among 43 managers who were in different industries in west part of Iran. Most of the people who participated in our survey were male and they were between 25 to 30 years old. The study considers relationship between leadership style and conflict management, which includes the relationship between relationship-oriented and task-oriented leaderships with avoiding conflict management strategy, solution and control based conflict managements. The results confirmed that there is only a meaningful relationship between relationship-oriented leadership with solution-based conflict management. In other words, our survey indicates that when there is a conflict, management can handle the problem using his/her relationship and find appropriate solution to resolve any possible conflict

Intracanal Retention of Glass Fiber Posts

Objective: Fiber-reinforced composite (FRC) posts have recently become more popular for restoring endodontically treated teeth because of providing esthetics, better stress distribution and lower risk  of root fracture. Resistance against tensile forces dislodging the post from the root canal is a prerequisite for these posts. This study aimed to evaluate the tensile retention (strength) of intracanal glass fiber posts produced by three manufacturers.Methods: In this interventional study, the crowns of 30 sound human maxillary central incisors were cut at the cementoenamel junction and the roots were endodontically treated. Post space was prepared to a length of 10mm and the specimens were divided into three groups of 10. HtCo, Anthogyr and Svenskposts were used in groups 1, 2 and 3, respectively. The posts were cemented with Panavia F2 resin cement according to the manufacturer’s instructions. Specimens were then immersed in water at 37°C for 30 days and were then subjected to 7500 thermal cycles between 5- 55°C. Intracanal tensile retention (strength) was measured at a crosshead speed of 0.5 mm/min. Data were analyzed using one-way ANOVA at p&lt;0.05 level of significance.Results: The mean retention was 188.53 (15.43), 183.81 (16.37) and 192.19 (17.50) N in Htco, Anthogyr and Svensk posts, respectively. Statistical analyses showed no significant difference in this regard among groups (p=0.111).Conclusion: Within the limitations of this study, retention of HtCo glass fiber posts in the root  canals was similar to that of two other posts

The impact of employing a magnetic field as well as Fe3O4 nanoparticles on the performance of phase change materials

In this study a 2Dcubic chamber model filled with paraffin is analyzed with and without the inclusion of magnetic Fe3O4 nanoparticles at concentrations of 0.5, 1, 1.5 and 2 wt%, and an external magnetic field of intensities 0.005, 0.01, 0.015 and 0.02 T. It is ascertained that adding magnetic nanoparticles leads the horizontal temperature gradient to be reduced owing to increments in thermal conductivity. Additionally, this feature is found to be accelerated by applying an external magnetic field, which shapes highly conductive cluster formations of nanoparticles. However, since the increase in nanoparticle concentration and magnetic intensity increases the composite viscosity, there is an optimum configuration while applying both schemes. As such, the addition of 1 wt% nanoparticles provides the best results, as the melting time is reduced up to 25% compared to pure paraffin. Meanwhile, the melting time of a 1 wt% nanoparticle-containing phase change material (PCM) in the presence of an external magnetic field is improved up to 24% compared to the case with no external magnetic field. Also, the heat transfer coefficient of a 1 wt% nanoparticle-containing PCM both with and without an external magnetic field is also staggeringly enhanced compared to pure paraffin. Good correspondence with experimental data was achieved.https://www.tandfonline.com/loi/tcfm20am2022Mechanical and Aeronautical Engineerin

Spatio-temporal epidemiology of the tuberculosis incidence rate in Iran 2008 to 2018

Abstract Background Effective reduction of tuberculosis (TB) requires information on the distribution of TB incidence rate across time and location. This study aims to identify the spatio-temporal pattern of TB incidence rate in Iran between 2008 and 2018. Methods This cross-sectional study was conducted on aggregated TB data (50,500 patients) at the provincial level provided by the Ministry of Health in Iran between 2008 and 2018. The Anselin Local Moran’s I and Getis-Ord Gi* were performed to identify the spatial variations of the disease. Furthermore, spatial scan statistic was employed for purely temporal and spatio-temporal analyses. In all instances, the null hypothesis of no clusters was rejected at p ≤ 0.05. Results The overall incidence rate of TB decreased from 13.46 per 100,000 (95% CI: 13.19–13.73) in 2008 to 10.88 per 100,000 (95% CI: 10.65–11.11) in 2018. The highest incidence rate of TB was observed in southeast and northeast of Iran for the whole study period. Additionally, spatial cluster analysis discovered Khuzestan Province, in the West of the country, having significantly higher rates than neighbouring provinces in terms of both total TB and smear-positive pulmonary TB (SPPTB). Purely temporal analysis showed that high-rate and low-rate clusters were predominantly distributed in the time periods 2010–2014 and 2017–2018. Spatio-temporal results showed that the statistically significant clusters were mainly distributed from centre to the east during the study period. Some high-trend TB and SPPTB statistically significant clusters were found. Conclusion The results provided an overview of the latest TB spatio-temporal status In Iran and identified decreasing trends of TB in the 2008–2018 period. Despite the decreasing incidence rate, there is still need for screening, and targeting of preventive interventions, especially in high-risk areas. Knowledge of the spatio-temporal pattern of TB can be useful for policy development as the information regarding the high-risk areas would contribute to the selection of areas needed to be targeted for the expansion of health facilities