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Issue Info: 
  • Year: 

    2023
  • Volume: 

    53
  • Issue: 

    1
  • Pages: 

    69-79
Measures: 
  • Citations: 

    0
  • Views: 

    200
  • Downloads: 

    43
Abstract: 

In this paper, a novel risk-based, two-objective (technical and economical) OPTIMAL reactive power dispatch method in a wind-integrated power system is proposed which is more consistent with operational criteria.  The technical objective includes the minimization of the new voltage instability risk index. The economical objective includes cost minimization of reactive power generation and active power loss. The proposed voltage instability risk employs a hybrid possibilistic (Delphi-Fuzzy)-probabilistic approach that takes into consideration the operator’s experience, the wind speed and demand forecast uncertainties when quantifying the risk index. The decision variables are the reactive power resources of the system. To solve the problem, the modified multi-objective particle swarm optimization algorithm with sine and cosine acceleration coefficients is utilized. The method is implemented on the modified IEEE 30-bus system. The proposed method is compared with those in the previously published literature, and the results confirm that the proposed risk index is better at estimating the voltage instability risk of the system, especially in cases with severe impact and low probability. In addition, according to the simulation results compared to typical security-based planning, the proposed risk-based planning may increase the security and economy of the system due to better utilization of system resources.

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Author(s): 

Pasha Nima | Jolai Fariborz | Razavi Haji Agha Seyyed Hosein

Issue Info: 
  • Year: 

    2024
  • Volume: 

    16
  • Issue: 

    4
  • Pages: 

    535-559
Measures: 
  • Citations: 

    0
  • Views: 

    13
  • Downloads: 

    0
Abstract: 

Objective Flexible Manufacturing Systems (FMS) are integrated workstations that utilize computer-controlled equipment components for production. These systems are managed by a central computer, which significantly enhances the efficiency and productivity of the production process. Accordingly, a case study is conducted on an FMS electrical manufacturing system with complex manufacturing processes, where automation on the production line is crucial. Selecting the OPTIMAL number of advanced equipment is a challenging and vital issue for managers aiming to boost productivity and efficiently fulfill customer orders. It is a hard-to-change model, and replacing equipment incurs substantial costs.   Methods This study employs the two-stage D-OPTIMAL method to optimize the combination of FMS elements and equipment. The D-OPTIMAL response level input is derived from discrete-event simulation results. Depending on the conditions, various FMS equipment is allocated to each process. Each simulation result for element combinations serves as input for the experimental design. Additionally, the response level (y) of experiments from various FMS indexes is calculated using a weighting method. To reduce the number of experiments and increase data accuracy in a case study with hard-to-change parameters, all combinations are categorized based on the number of automated and manual equipment. The two stages of the D-OPTIMAL design are defined as follows: In the first stage, all combinations within these categories are investigated. In the second stage, the optimized combination from the first stage is analyzed to determine the best configuration. Experiments in the top category from the first stage are simulated and further evaluated in the second stage of the D-OPTIMAL method.   Results In the first phase, all advanced production equipment and FMS elements were considered. After selecting the best-calculated “y” value, which was 147,133.09 in this category, another D-OPTIMAL design was optimized in the second phase to determine the best combination. This combination yielded a “y” value of 151,317.88, representing an improvement over the best category in the first phase of the D-OPTIMAL design. Consequently, the optimized combination from the first phase was further refined. The results from the developed D-OPTIMAL method and the second phase indicate that the OPTIMAL combination of equipment involves using automated and FMS equipment for approximately 92.8% of the total components. Finally, a list of recommended FMS equipment is provided, and its productivity is compared with the productivity at the current level and a higher degree of automation for this production line.   Conclusion In summary, the results of the experimental design show that using advanced production systems does not necessarily improve system efficiency, and determining OPTIMAL combinations requires accurate calculations.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

HASSANI M. | AMANI M.

Issue Info: 
  • Year: 

    2010
  • Volume: 

    18
  • Issue: 

    2 (40)
  • Pages: 

    163-176
Measures: 
  • Citations: 

    0
  • Views: 

    895
  • Downloads: 

    0
Abstract: 

In order to study the spatial structure of oriental beech (Fagus orientalis Lipsky) stand at OPTIMAL stage, this research was carried out in the Caspian forests of Iran. The studied site consisted of a natural stand located at Sangdeh district (Mers-e-se) with three hectare area. It is located between 1900 and1950 m.a.s.l. Six sample plots each with 0.36 ha area, were systematically selected and all trees (1244 stem) within the plots were measured and recorded. Using increment borer, the mean age of the stand was estimated as 137 years; the age difference of trees was 40 years. Results showed that the stand has a closed canopy cover and distribution of stem number per diameter class was more or less homogenous (Bell shape) with a semi even-aged structure. Using Ripley's K function, the distribution of trees within the stand was random.

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    34
  • Issue: 

    1
  • Pages: 

    117-127
Measures: 
  • Citations: 

    0
  • Views: 

    52
  • Downloads: 

    12
Abstract: 

This study aimed to investigate the effect of different culture mediums based on the Walne medium on the growth rate, chemical composition, and fatty acid (FA) profile in I. galbana and N. oculata. This experiment was done in a factorial design with two culture media (Walne and modified Walne media) and two microalgae species, including I. galbana and N. oculata. The results showed that the modified culture medium increased total and daily fresh and dried biomass production of I. galbana and N. oculata. Modified culture media increased crude fat (CF) and crude protein (CP) content and total and daily lipid production in both the studied species. However, in both the studied culture mediums, N. oculata had higher growth and production performance compared to I. galbana. Modified growth media also affects the FA profiles of the studied microalgae species. Total saturated and unsaturated FA content was not influenced by the growth medium but modified media increased poly unsaturated FA (PUFA) at the expense of mono unsaturated FA (MUFA). Omega- 3 FA content (linolenic acid, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA)) was increased as a result of the medium modification in both species. However, linoleic acid content was affected differently in I. galbana and N. oculata. The linoleic acid concentration was reduced in modified medium grown N. oculata but increased in I. galbana. Palmitic acid and stearic acid contents were also decreased in both of the studied species in the modified medium. This study develops microalgal cultivation using a modified Walne medium for higher CP, CF, EPA, DHA contents, the ratio of omega3: omega6 FA, and biomass production in N. oculata and I. galbana microalgae.Microalgae species can produce oil and protein in non-cultivable lands, reducing the need for defrosting and can have an important role in reducing carbon foot-print of animal production. One of the most valuable products of microalgae is their oil, which ranges from 20 to 50% of the dry weight of microalgae (Brennan and Owende 2010; Leonga et al. 2018). The I. galbana is often grown on farms to produce oils that contain large amounts of PUFA rich in omega-3 long chain FA, such as EPA and DHA (Gouveia et al. 2008). Species of the genus N. oculata are also known to be rich in EPA (Kagan et al. 2014; Borges et al. 2016). Factors such as nutrient quantity and quality, light, pH, turbulence, salinity, and temperature are the most important parameters on which, the growth of microalgae depends (Lavens and Sorgeloos 1996; Converti et al. 2009; Emmanuel and Nelson 2016). Vitamins regulate biochemical reactions in microalgae (Hakalin et al. 2014) and the growth rate of some microalgae species is highly dependent on some the vitamins such as cobalamin, biotin and thiamine (Tandon et al. 2017). However, the effect of vitamins on the growth, diversity, and productivity of microalgae has been poorly studied (Arif et al. 2019). The effects of different Nitrogen and phosphorus concentration as the main limiting nutrients on growth performance and biomass production of I. galbana and N. oculata had been evaluated previously (Andersen 2005; Zarrinmehr et al. 2020). However, there was not any report about effects of modifying the availability of culture medium sources of nitrogen and phosphorus. In the composition of the Walne medium, No3-, Po4-, and Cl- are considered as anions, and Na+, Mn+, Co+, Zn+, and Cu+ are considered as cations. Cations chelating anions and making them less available to microalgae. So, we hypothesize that changing the concentration of cations in the culture media, without increasing the concentration of N and P sources, will change the availability of anionic compounds for microalgae and consequently affects microalgal production and composition. Therefore, the effects of lower levels of cations including ZnCl2, CoCl2. 6H2O, (NH4)6Mn7O24, and CuSo4. 5H2O and higher levels of B1 and B12 vitamin in Walne medium on the growth rate, biomass production performance, chemical composition, and fatty acid profile of I. galbana and N. oculata, were investigated in this study. This study aimed to investigate the effect of different culture mediums based on the Walne medium on the growth rate, chemical composition, and fatty acid (FA) profile in I. galbana and N. oculata. This experiment was done in a factorial design with two culture media (Walne and modified Walne media) and two microalgae species, including I. galbana and N. oculata. The results showed that the modified culture medium increased total and daily fresh and dried biomass production of I. galbana and N. oculata. Modified culture media increased crude fat (CF) and crude protein (CP) content and total and daily lipid production in both the studied species. However, in both the studied culture mediums, N. oculata had higher growth and production performance compared to I. galbana. Modified growth media also affects the FA profiles of the studied microalgae species. Total saturated and unsaturated FA content was not influenced by the growth medium but modified media increased poly unsaturated FA (PUFA) at the expense of mono unsaturated FA (MUFA). Omega- 3 FA content (linolenic acid, Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA)) was increased as a result of the medium modification in both species. However, linoleic acid content was affected differently in I. galbana and N. oculata. The linoleic acid concentration was reduced in modified medium grown N. oculata but increased in I. galbana. Palmitic acid and stearic acid contents were also decreased in both of the studied species in the modified medium. This study develops microalgal cultivation using a modified Walne medium for higher CP, CF, EPA, DHA contents, the ratio of omega3: omega6 FA, and biomass production in N. oculata and I. galbana microalgae.

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    55
  • Issue: 

    2
  • Pages: 

    319-336
Measures: 
  • Citations: 

    0
  • Views: 

    72
  • Downloads: 

    17
Abstract: 

Using the control tools is an efficient method to decrease the responses of the structure under external excitations. In this regard, this study investigates the performance of two structures equipped with MR dampers and Orifice dampers under blast-induced vibration. In addition to stimulating the underground blast-induced vibration (due to the different nature of these loads), seismic excitation has also been used to evaluate the efficiency of these dampers. These dampers are semi-active devices, which change the output force of the damper by changing the input voltage and magnetic field of dampers. Also, in this paper, clipped-OPTIMAL algorithm was used. This algorithm can generate OPTIMAL damper force by changing the voltage at each time step based on the input forces. In this research, structural responses based on OPTIMAL and maximum voltage are considered. Also, the numerical results of the structure are compared with LQR algorithm. The LQR algorithm is considered a criterion for reducing structural responses to blast-induced vibration. The results indicate that the proposed method (the different locations and types of dampers) is efficient for decreasing the responses of the structure.

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Author(s): 

TAHMASEBI M. | SHOKR ELAHI E.

Issue Info: 
  • Year: 

    2010
  • Volume: 

    7
  • Issue: 

    SUPPLEMENT 1 (26TH IRANIAN CONGRESS OF RADIOLOGY)
  • Pages: 

    0-0
Measures: 
  • Citations: 

    0
  • Views: 

    189
  • Downloads: 

    0
Keywords: 
Abstract: 

The radiological report is the medical document that qualifies the radiologist as a clinician and as a specialist, because through it radiologists expresse their professionalism.There is nothing more debatable than the report and how it should be written. It is conditioned by many variables that derive from the wide variety of sensitivities and personal or local cultures. In addition, there has never been a specific school in which these rules are taught.In the assessment of each written material, two things are explained:1. Methodology of the writing process itself as an act2. Characters of the written material In assessing the method of writing a radiological report, two dimensions are discussed: 1. Hardware: including data gathering, their processing and preparing them to be seen, the method of reporting, conditions of workspace, instruments and all the physical parts of the work.2. Software: how someone watches the images, methodology of thought and logical reasoning, and ultimately, how pictures are transferred to understandable, meaningful and useful written material.In assessing the characters of the written material itself, we should note:1. The configuration includes the structure of the words and grammar, style of writing, order of things to come after each other. This is the carrier of the content. 2. The content is the main reason of the writing which contains the whole meaning and all parts of what one wants his or her audience to get from the note.

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Author(s): 

ABEL A.B.

Issue Info: 
  • Year: 

    1987
  • Volume: 

    19
  • Issue: 

    3
  • Pages: 

    437-450
Measures: 
  • Citations: 

    1
  • Views: 

    114
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    11
  • Issue: 

    2
  • Pages: 

    85-97
Measures: 
  • Citations: 

    0
  • Views: 

    44
  • Downloads: 

    2
Abstract: 

An OPTIMAL labeling of a graph with $n$ vertices and $m$ edges is an injective assignment of the first $n$ nonnegative integers to the vertices‎, ‎that induces‎, ‎for each edge‎, ‎a weight given by the sum of the labels of its end-vertices with the property that the set of all induced weights consists of the first $m$ positive integers‎. ‎We explore the connection of this labeling with other well-known functions such as super edge-magic and $\alpha$-labelings‎. ‎A graph with $n$ vertices is maximal when the number of edges is $2n-3$; all the results included in this work are about maximal graphs‎. ‎We determine the number of OPTIMALly labeled graphs using the adjacency matrix‎. ‎Several techniques to construct maximal graphs that admit an OPTIMAL labeling are introduced as well as a family of outerplanar graphs that can be labeled in this form.

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Author(s): 

SUMMERS LAWRENCE H.

Issue Info: 
  • Year: 

    1981
  • Volume: 

    7
  • Issue: 

    2
  • Pages: 

    175-194
Measures: 
  • Citations: 

    1
  • Views: 

    126
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2003
  • Volume: 

    70
  • Issue: 

    4
  • Pages: 

    825-860
Measures: 
  • Citations: 

    1
  • Views: 

    158
  • Downloads: 

    0
Keywords: 
Abstract: 

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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