Optimal Pattern Research Articles

Wheat Cultivation and Nutrient Control for the 180-day CELSS Integrated Experiment

This research aimed to select the well-adapted wheat cultivar and to explore an optimum nutrient control pattern for wheat cultivation in the 180-day integrated experiment of controlled ecological life support system (CELSS). In the experiment, six wheat cultivars from different areas of China were preselected and cultivated in four separate recirculating hydroponic systems (HySy), nutrients in which could be controlled and recycled according the values of pH, electrical conductivity (EC) and dissolved oxygen (DO). Wheat covered an area of 111.3 m2 and had been planted in 17 batches with a 15-day time interval to realize stable regeneration of oxygen, water and food during the 180-day duration in the closed cabin. The results indicated that different cultivars displayed different adaptabilities to the controlled environment. Wt04 had a stronger adaptability with the highest yield (12.82 g DM m−2 d−1) and edible radiation use efficiency (RUE) (0.28 g DM mol−1) whereas Wt06 adapted this environment poorly because of its excessive vegetative growth. For the morphological characters, wheat plants tended to dwarf in the CELSS environment compared with the field. An innovative controlling pattern was established for nutrient supplement. Through the real-time monitoring of pH, EC and DO of the nutrient solution and the periodical detection of the contents of nutrient elements, the nutrient solution could be controlled and recycled continuously without being renewed under a suitable state for wheat plants growth during the 180-day integrated experiment.

Leveraging real world data and AIML to inform smart patient care in oncology.

e20002 Background: Identifying optimal therapy options can help maximize treatment outcomes. Finding ways to help improve treatment decision is of great value to achieve better patient care. With the availability of robust patient real world data and the application of state of the art Artificial Intelligence and Machine Learning (AIML) technology, new opportunities have emerged for a broad spectrum of research needs from oncology R&D to commercialization. To illustrate the above advancements, this study identified patients diagnosed with CLL who may progress to next line of treatment in the near future (e.g. future 3 months). More importantly, we can identify treatment patterns which are more effective in treating different types of CLL patients. Methods: This study includes multiple steps which have already been analyzed for feasibility: 1. Collect CLL patients. IQVIA's real world data contains ~60,000 active CLL treated patients. ~2,000 patients have progressed line of treatment in 3 month. 2. Define patients into positive and negative cohorts based on those who have/have not advanced to line L2+. 3. Determine patient profiles based on treatment regimens, symptoms, lab tests, doctor visits, hospital visits, and co-morbidity, etc. 4. Select patient and treatment features to fit an AIML predictive model. 5. Test different algorithms to achieve best model results and validate model performance. 6. Score and classify CLL patients into high and low probability based on the predictive model. 7. Match patients based on feature importance and compare regimens between positive and negative cohort. Results: Model accuracy is above 90%. Top clinical features are calculated for each patient. Optimum treatment patterns between high and low probability patients are identified, with controlling patient key features. Conclusions: Conclusions from this study is expected to yield deeper insight into more tailored treatments by patient type. CLL patients started with oral therapy(targeting) have better response than other treatments.

Thermal and Thermomechanical Behaviors of the Fan-Out Package With Embedded Ag Patterns

Fan-out wafer/panel level package (PLP) is an advanced package. Compared to the conventional package, its thickness is reduced, and electrical and thermal characteristics are improved, through the substitution of a substrate/interposer with a redistribution layer (RDL). However, its thermal and thermomechanical characteristics need to be improved and controlled more elaborately. In this article, six types of Ag patterns were embedded in the upper side of the fan-out package. Thermal emission was improved by building an efficient thermal conductive path, while warpage was improved by vertical symmetry and strain distribution. Overall, the large pattern in both fan-out and fan-in zones reduced the warpage and the pattern embedded in the fan-in zone efficiently improved the thermal emission. However, the pattern area should be designed by considering the overlapped areas with the through via interconnection or the embedded component in the fan-out zone. Because the embedded pattern with a large area is not necessarily a proper approach, an optimum pattern was studied with the simulation and measurement of the thermogram and warpage. The approach of the embedding pattern in the fan-out package is expected to improve its thermal and thermomechanical behaviors.

The Hybrid Compression Moulding of Structural Composite Materials for Automotive Applications

The Innovate-UK-funded Composite Lightweight Automotive Suspension System (CLASS) project, led by Ford Motor Company and partnered by Gestamp UK, GRM Consulting and WMG, investigated the use of carbon fibre reinforced composite materials to decrease the weight of a complex automotive rear suspension component in support of reduction in vehicle emissions. A multi-material design comprising discontinuous fibre composite (C-SMC), aligned fibre composite laminate (prepreg) and steel was developed. A high volume hybrid compression moulding manufacturing process was developed at WMG, achieving total press cycle times of around 5 minutes. Prototype parts were manufactured and evaluated using materials characterisation techniques to validate the manufacturing methods. The optimum C-SMC charge pattern was investigated to achieve complete fill with minimal pre-processing. Destructive and nondestructive analysis of the hybrid parts was performed to understand resultant hybrid material macrostructure. This innovative design and manufacturing process resulted in a component 35% lighter than the original multi-piece steel design.

MEMS piezoresistive pressure sensor with patterned thinning of diaphragm

PurposeThe purpose of this study is to find a new design that can increase the sensitivity of the sensor without sacrificing the linearity. A novel and very efficient method for increasing the sensitivity of MEMS pressure sensor has been proposed for the first time. Rather than perforation, we propose patterned thinning of the diaphragm so that specific regions on it are thinner. This method allows the diaphragm to deflect more in response with regard to the pressure. The best excavation depth has been calculated and a pressure sensor with an optimal pattern for thinned regions has been designed. Compared to the perforated diaphragm with the same pattern, larger output voltage is achieved for the proposed sensor. Unlike the perforations that have to be near the edges of the diaphragm, it is possible for the thin regions to be placed around the center of the diaphragm. This significantly increases the sensitivity of the sensor. In our designation, we have reached a 60 per cent thinning (of the diaphragm area) while perforations larger than 40 per cent degrade the operation of the sensor. The proposed method is applicable to other MEMS sensors and actuators and improves their ultimate performance.Design/methodology/approachInstead of perforating the diaphragm, we propose a patterned thinning scheme which improves the sensor performance.FindingsBy using thinned regions on the diaphragm rather than perforations, the sensitivity of the sensor was improved. The simulation results show that the proposed design provides larger membrane deflections and higher output voltages compared to the pressure sensors with a normal or perforated diaphragm.Originality/valueThe proposed MEMS piezoelectric pressure sensor for the first time takes advantage of thinned diaphragm with optimum pattern of thinned regions, larger outputs and larger sensitivity compared with the simple or perforated diaphragm pressure sensors.

Maximizing crops yield net benefit in a groundwater-irrigated plain constrained to aquifer stable depletion using a coupled PSO-SWAT-MODFLOW hydro-agronomic model

Groundwater is a strategic resource for irrigated agriculture particularly in arid regions. Management of groundwater resources is essential to preserve sustainability while conserving economic interests. In this research, crops areas and water depletion by wells in an agricultural plain are optimized. This done by a novel hydro-agronomic-based simulation-optimization approach in which SWAT as the agronomic and MODFLOW as the groundwater simulation models are coupled with the Particle Swarm Optimization (PSO) algorithm. Maximization of the net benefit gained from crops production is defined as the objective function. The decision variables are cultivation area for four major irrigated crops and irrigation depths (groundwater withdrawals). Groundwater depletion for irrigation is limited to a pre-defined value as the stability level. The PSO-SWAT-MODFLOW model is applied for Asemanabad plain in west of Iran. Results show that by optimum crops area and irrigation planning the agricultural net benefit is increased significantly comparing the present situation existing in the plain while the aquifer’s depletion remains in the stable range. By sensitivity analyses, it is found that the crops’ price has a major effect on the optimum cropping pattern and water consumption while improvement of the irrigation efficiency has a negligible impact on the plain’s optimum agricultural net benefit.

Effect of Gibberellic Acid on Production of Biomass, Polyphenolics and Steviol Glycosides in Adventitious Root Cultures of Stevia rebaudiana (Bert.).

In current study, the effect of gibberellic acid was tested for production of biomass, polyphenolics and Steviol glycosides in adventitious root cultures of Stevia rebaudiana. Adventitious cultures were induced from the roots of in vitro grown plantlets on Murashige and Skoog (MS) medium containing combination of gibberellic acid (GA3; 0.5, 1.0, 1.5 and 2.0 mg/L) and naphthalene acetic acid (NAA; 0.5 mg/L). Initially, a known mass of inoculum roots were shifted into suspension media augmented with various GA3 concentrations. The growth behavior of adventitious roots was recorded every 3 days for a period of 30 days. Maximum biomass biosynthesis (13.12 g/flask) was noticed in exponential phase on 27th day in the suspension containing 2.0 mg/L of GA3. Other GA3 concentrations also displayed optimum patterns of biomass accumulation as compared to the control. Adventitious roots were investigated for total phenolic content (TPC) and production (TPP), total flavonoid content (TFC) and production (TFP), and 1, 1-diphenyl-2-picrylhydrazyl (DPPH)-based antioxidant potential. Maximum phenolics (TPC 9.84 mg gallic acid equivalent (GAE)/g-dry weight (DW)) and TPP (147.6 mg/L), TFC (5.12 mg Quercitin equivalent (QE)/g-DW) and TFP (76.91 mg/L) were observed in 2.0 mg/L GA3 treated cultures. The same concentration of gibberellic acid enhanced antioxidant activity (77.2%). Furthermore, maximum stevioside (7.13 mg/g-DW), rebaudioside-A (0.27 mg/g-DW) and dulcoside-A (0.001 mg/g-DW) were observed in roots exposed to 2.0 mg/L GA3. This is the first report on the application of GA3 on biomass accumulation and secondary metabolite production in S. rebaudiana. The current study will be helpful to scale up the adventitious root cultures in bioreactors for the production of biomass and pharmaceutically important secondary metabolites.

Effects of plastic mulch and nitrogen fertilizer on the soil microbial community, enzymatic activity and yield performance in a dryland maize cropping system

AbstractFarming practices that integrate plastic film mulching and nitrogen (N) fertilization have been extensively used to enhance crop productivity. However, the interactive effects of mulching and N application on soil microbial properties and crop yields have received little attention. A 2‐year field experiment was carried out in the Loess Plateau to investigate the independent and combined effects of plastic mulch and N application rate on the soil microbial population, enzymatic activity and grain yield. From 2016 to 2017, two mulching patterns (i.e., plastic mulching and no mulching) were exposed to five different N application rates (0 (N0), 80 (N80), 160 (N160), 200 (N200) and 240 (N240) kg N ha−1). N application significantly affected the soil microbial community composition, as suggested by significant increases in soil total bacteria, cellulose‐decomposing bacteria and the bacterial‐to‐fungal ratio with N rates. In contrast, the mulching pattern significantly affected soil extracellular enzyme production. Furthermore, there were significant effects of mulching, N application and their interaction on grain yield. The highest grain yield (11,728 kg N ha−1 in 2016 and 12,350 kg N ha−1 in 2017) in both growing seasons was consistently obtained under plastic mulching with a N level of 200 kg N ha−1. Our study showed that plastic mulching significantly affected extracellular enzyme production, and N fertilizer application significantly affected the composition of the soil microbial community.Highlights Independent and coupled effects of mulching and N application on soil biological properties and grain performance were explored. N application significantly influenced soil microbial community composition. Mulching pattern rather than N application independently and significantly affected soil extracellular enzyme production The combined application of plastic mulching with 200 kg N ha−1 should be seem as an optimum crop production pattern in this area.

Optimizing rectangular fins for natural convection cooling using CFD

Efficient heat transfer from finned-surfaces under natural convection is a critical consideration in the design of heat sinks for microelectronics and thermal devices. Previous experimental studies on natural convection from rectangular fins on horizontal surfaces have shown that maximum heat transfer per unit base area occurs within a narrow range of fin spacing in tall fins, and over a wider range of fin spacing in shallow fins. However, the heat transfer and flow characteristics of optimum fin configurations and the combined effects of fin geometrical parameters have not been sufficiently scrutinized in the literature. This work is primarily focused on characterizing the optimum heat transfer and flow patterns using three-dimensional, steady-state, laminar, conjugate heat transfer simulations, which serve as the fundamental basis for determining optimum fins. The main fin design parameters are the fin spacing, height, and length. Multi-parametric computational fluid dynamics (CFD) optimization was conducted to determine the combined effects of fin spacing, height, and length on heat transfer. To find a global optimum fin design, we performed a multi-parametric optimization using the dynamic-Q algorithm, rather than through a single parameter variation as is commonly done in previous studies. It was found that the fin spacing, height, and length strongly affect the flow through the fin channel ends, and hence the temperature gradient and heat transfer rate from the fin surfaces. The results demonstrate that the dynamic-Q optimization could efficiently find the global optimum CFD solutions for the design objectives: the maximum heat transfer per unit base area and the maximum heat transfer per unit base area and fin weight. The results are validated through the experimental results available for typical fin designs, as well as an experimental measurement of an example fin design in this work.

Control of Marangoni-driven patterning by an optimized distribution of surface energy

We computationally demonstrate a method to control Marangoni-driven flows and create patterns with sharp features on polymer films by optimizing the spatial variation of surface energy or tension. This Marangoni-driven patterning (MDP) uses the variations in surface tension to drive fluid flow. By selectively exposing a thin polymer film to UV light, a photochemical reaction takes place, which subsequently alters the surface tension of the polymer film in the exposed regions. On heating above its glass transition temperature, the polymer flows from regions of lower to higher surface tension to form hill-and-valley features. A barrier to advancing the application of MDP is that the flow will often dull sharp features and degrade the fidelity of the desired pattern. To compensate a pixel-based optimization of the surface energy or equivalently, the photoexposure pattern is developed. A genetic algorithm is used to search for the optimum photoexposure pattern based on simulations of the flow, which includes Marangoni and capillary forces and diffusion of the surface tension promoter. The optimization of the photoexposure pattern significantly improves the fidelity of the desired final pattern for a wide range of annealing temperatures and times. Guidelines for successful MDP are identified based on ratios of characteristic times for the Marangoni and capillary flows and lateral diffusion.

Modeling of linear programming for electrical energy generation power plant:an application of economic optimization approach

PT. KDLC Indonesia has five units of electrical energy generators with a total capacity of 400 MW. Each unit consists of one Boiler and one Turbine Generator. All fiveunits are using a manifold system that makes the Boilers and Turbine Generators from different units able to operate interchangeably. This paper studies how to determine a combined path of an optimum electricity production activity using Linear Programming method.It is suggested some steps, as well, that can be run to solve a problem with the help of POM software during the calculation process. According to Linear Programming, an optimum generation pattern is influenced by the demand factor, production capacity, raw material stock, operational cost, and efficiency of every unit. With an optimum combination of those aspects, the need of raw materials for each operating unit will be found out; in this way, therefore, a continuous and steady supply of raw materials can be maintained,and eventually an optimum electrical energy generating process finally results.

Differences of wheat yield and economic benefits between soybean-wheat and rice-wheat cropping under different nitrogen fertilization patterns in Jianghan Plain, China

We analyzed winter wheat yield and growth pattern of soybean-wheat and rice-wheat rotation systems in response to different nitrogen fertilization patterns with the aim to provide theoretical basis for narrowing the wheat yield gap between the two rotations in Jianghan Plain. Field experiments were conducted with three treatments, control without nitrogen, traditional nitrogen management (70% nitrogen as basal and 30% nitrogen as topdressing at overwintering), and improved nitrogen management (one third of N was applied at sowing, wintering and jointing, respectively). The growth pattern, grain yield, yield components, fertilizer use-efficiency and economic benefit under the different nitrogen fertilization patterns were examined. Results showed that grain yield was significantly affected by both nitrogen fertilization pattern and crop rotation. Grain yield under improved nitrogen treatment was significantly higher, with the yield gap being 920 kg·hm-2 in soybean-wheat rotation and 2195 kg·hm-2 in rice-wheat rotation. Traditional nitrogen management showed advantage in establishing winter and spring population. Dry matter accumulation was higher under improved nitrogen treatment than traditional treatment with 5%-31% and 14%-28% increases for soybean-wheat and rice-wheat rotations, respectively. The higher yield in the soybean-wheat rotation was due to greater panicle numbers, higher percentage of tiller ears, and dry matter accumulation. The rice-wheat rotation under improved nitrogen showed a significant increase in grain yield compared with soybean-wheat rotation. This result indicated that yield gap between the two crop rotations could be narrowed through suitable nitrogen management. Grain weight after anthesis showed "slow-fast-medium" in soybean-wheat rotation and "medium-fast-slow" in rice-wheat rotation. Nitrogen use efficiency and net benefit of wheat season were higher in rice-wheat system. Overall, the rice-wheat system showed obvious advantages in population structure, dry matter accumulation, grain yield and benefit under improved nitrogen pattern, which was the optimum pattern for both wheat yield and benefit in Jianghan Plain.

Effects of Plant Density and Planting Pattern on Growth and Seed Yield of Groundnuts [Arachis hypogaea (l.)] in the Wet Middleveld of Eswatini

The most appropriate plant density and planting pattern to use for optimum growth and yield of groundnuts (Arachis hypogaea L.) in Eswatini among those currently used is not known, as the patterns are highly influenced by environmental conditions in specific regions. A field trial was conducted with the objective of determining the optimum plant density and planting pattern for groundnut in the Wet Middleveld of Eswatini. The experiment was conducted at the University of Eswatini, Luyengo Campus during the 2018/2019 cropping. The treatments consisted of three planting densities (i.e. 88,889 plants/ha, 44,444 plants/ha, and 29,630 plants/ha) and two planting patterns (i.e. Ridges and Raisedbeds) in a split plot arrangement. Results showed that all the measured parameters including seed yield were not significantly different in all treatments. However, the highest seed yield was obtained at low plant density which was 71.4 kg/ha followed by 568 kg/ha at medium and the least was 434 kg/ha at high plant density. The high plant density (88889 plants/ha) obtained the highest value of dry biomass (13018 kg/ha) at ridges which was higher than 3859 kg/ha obtained at the low plant density (29630 plants/ha) at raised beds at R6 growth stage. The ridges at the intermediate plant density (44444 plants per hectare) obtained the highest shelling percentage of 59.67% while the lowest (56%) shelling percentage was obtained at raised beds at 88889 plants per hectare. It is concluded that groundnuts at raised beds with low plant density yielded higher than those at ridges with high plant density. It is therefore, recommended that groundnuts be planted at raised beds with low plant density to increase groundnut production and for ease of harvesting.

What is the Optimum Pattern of Pressurisation to Gain Maximum Penetration of Methylmethacrylate Cement into the Reamed Acetabulum?

IntroductionThe cemented polyethylene cup has remained the standard acetabular implant for 50 years although there has been little research into cementing techniques. In the past, cement was previously inserted by sequential manual pressurisation (thumbing) but this technique was prone to contamination of the cement leading to weakening of fixation. In recent times, third-generation techniques using sealed pressurisation with rim preparation have been espoused with similar results. We were interested in establishing whether repeated cycles of compression of cement allowing adequate time for relaxation increases its depth of penetration, and the optimum period of relaxation required to achieve this goal.MethodA single mix of polymethylmethacrylate cement at dough stage was inserted into a model of the reamed acetabulum. Cyclical pressurisation of the cement with 50 N followed nine different patterns to simulate thumbing, constant pressure, and the application of a sealed and unsealed acetabular cup implant.ResultsA constant load was as effective as all variations of repeated cycles of load and relaxation except for 50 N pressure applied for four seconds with four second intervals. A four second interval of relaxation achieved significantly more penetration than five or three seconds.Following two minutes of constant pressure, the application of a sealed or unsealed thrust of the plunger had no effect on cement penetration.ConclusionThis study suggests that optimal polymethylmethacrylate cement penetration into the acetabulum occurs with cycled application of load for four seconds followed by four seconds of relaxation. The subsequent pressurisation with either a flanged or unflanged acetabular implant does not appear to improve cement penetration.

Cropping pattern changes: A case study in Krishna delta region of Andhra Pradesh

A study was conducted to prepare a cropping pattern changes of Krishna delta region of Andhra Pradesh using satellite data, by following analysis in ERDAS and GIS environment. Sustainability of agriculture can be achieved through optimum cropping pattern or crop rotation in an area. Multi date satellite data of Landsat TM, IRS P6-LISS III and OLI satellite data were used for the generation of cropping pattern and extent of crops in kharif and rabi seasons. In the present study extent of crop in season wise and cropping pattern has been determined for rice, maize, sugarcane, cotton and rice-rice, rice-maize, respectively. Rice has been the dominant crop of kharif in the study area contributing to 59.77, 59.73 and 46.60 per cent followed by sugarcane contributing to 0.72, 1.46 and 1.81 per cent and cotton of 0.63, 0.50 and 1.07 per cent of the total geographical area in 1996, 2005 and 2015, respectively whereas, in rabi pulses were dominant crop and contributing of 44.09, 24.39 and 32.57 per cent of the total geographical area in 1996, 2005 and 2015, respectively followed by rice and maize. The extent of maize in the study area was found to be 53.43 and 76.86 (`000 ha) covering 8.56 and 12.32 per cent in 2006 and 2016, respectively. Temporal remote sensing data revealed a drastic reduction in extent of area in rice-pulse pattern with an increase in rice-maize in 2006 and 2016 compared to 1997.

Analysis of Changes in Ecological Patterns in the Upper Reaches of the Minjiang River One of Typical Disaster Prone Area of China

Mountain torrents and debris flows are rapid transport processes for soil and water materials in small watersheds in mountainous areas. They have a strong destructive power and often result in devastating natural disasters. Natural ecosystems can regulate natural disasters, reduce the risk of damage, increase the stability of disaster-prone environments and reduce the vulnerability of downstream areas. The upper reaches of the Minjiang River (URM) in Sichuan Province, China is a typical area prone to flood and debris flow disasters. An established scientific model was used to analyze land cover change in the URM to discover the optimum land use pattern. Based on the analysis of the pattern of temporal and spatial changes of ecosystems in the URM, the results showed that the amount of ecosystem change in the URM was small, and the overall change rate of ecosystems was only 1.7%. There was an obvious trend of landscape fragmentation in the whole URM region, and the change of ecosystems had clear regional differences. Human economic activities were the main reason for the changes in the spatial pattern of ecosystems from 1985 to 2013.

Exploring the Occurrence of Clogging in Highly Permeable Coarse Soils of Dam Foundations

Leakage through the permeable coarse soils of dam foundations in Tibet, China, lessened over time without any additional antiseepage measures. In fact, clogging generated during the infiltration process is recognized as the major factor in reducing leakage. A laboratory study was conducted to understand clogging in highly permeable coarse soil of a dam foundation with the primary aim of determining the clogging patterns and optimum clogging particle size (PS). Seven replicate experiments were constructed using soil media with PS ranges of 32–64 mm, 16–32 mm, 8–16 mm, 4–8 mm, 2–4 mm, 1‐2 mm, and 0.5–1 mm to observe clogging after feeding the soil media with sediments of different PSs. The experimental results showed that four clogging patterns were formed in different PSs of the coarse foundation soil. The ratio of the effective aperture of the soil Dea and the equivalent clogging particle size de(de/Dea) had a dominant effect on the four clogging patterns (surface clogging, (de/Dea) > 1; surface‐internal clogging, 0.5 < (de/Dea) ≤ 1; internal partial pore blockage, 0.25 < (de/Dea) ≤ 0.5; and unclogging, (de/Dea) ≤ 0.25). The assessment criterion of the optimum clogging pattern was determined by 0.5 < (de/Dea) ≤ 1, and from that, the optimum clogging PS do was calculated.

Impact of fused deposition process parameter (infill pattern) on the strength of PETG part

The manufacturing sector had a rapid development after the launching of additive manufacturing (AM) especially Fused Deposition Modelling (FDM) coming into act. It is like, innovation has found its own way to reach us. FDM is the technique where the operator can have various material mainly of thermoplastic nature, where the material is melted, extruded and deposited as layers one above the other resulting in the required product. Equally in FDM the design complication does not affect the production. Whereas, certain parameters namely layer thickness, raster angle, build-up orientation, air gap, etc., are taken into account. This paper studies about the tensile strength of the FDM produced component made of Polyethylene Terephthalate Glycol (PTEG) with the process parameter infill pattern is taken into consideration and all other parameters are kept constant. The test specimens were printed by varying the infill patterns but keeping the other parameters constant. The tensile strength of these test specimens was studied and the optimum infill pattern for better life of PTEG printed component was evaluated.

Optimum Pattern of Heater Element for Radome Achieving Enough Heating Ability and Millimeter Wave Transmissivity

Optimum Pattern of Heater Element for Radome Achieving Enough Heating Ability and Millimeter Wave Transmissivity

Retrofit Existing Frame Structures to Increase Their Economy and Sustainability in High Seismic Hazard Regions

The study proposes a retrofitting method with an optimum design of viscous dampers in order to improve the structural resistant capacity to earthquakes. The retrofitting method firstly uses a 2D frame model and places the viscous dampers in the structure to satisfy the performance requirements under code-specific design earthquake intensities and then performs an optimum design to increase the structural collapse-resistant capacity. The failure pattern analysis and fragility analysis show that the optimum design leads to better performance than the original frame structure. For regular structures, it is demonstrated that the optimum pattern of viscous damper placement obtained from a 2D frame model can be directly used in the retrofitting of the 3D frame model. The economic loss and repair time analyses are conducted for the retrofitted frame structure under different earthquake intensities, including the frequent earthquake, the occasional earthquake, and the rare earthquake. Although the proposed method is based on time-history analyses, it seems that the computational cost is acceptable because the 2D frame model is adopted to determine the optimum pattern of viscous damper placement; meanwhile, the owner can clearly know the economic benefits of the retrofitting under different earthquake intensities. The retrofitting also causes the frame to have reduced environmental problems (such as carbon emission) compared to the original frame in the repair process after a rare earthquake happens.