The outcomes of marginal donor hearts compared with ideal donors: a single-center experience in Iran

Behnam Shakerian,Sanaz Dehghani,Haleh Ashraf,Shahrokh Karbalai,Abbas Soleimani,Atieh Rezaeefar,Zahra Shajari,Hamidreza Hekmat,Marzieh Latifi,Azadeh Sadatnaseri 대한이식학회 2022 Korean Journal of Transplantation Vol.36 No.2

Background: Heart transplantation has been considered the gold-standard treatment for patients with end-stage heart failure. This study assessed the survival outcomes of mar- ginal donor hearts compared with ideal donor hearts in Iran. Methods: This retrospective study is based on the follow-up data of heart donors and recipients in the Sina Hospital Organ Procurement Unit. Among the 93 participants, 75 were categorized as ideal donors (group A) and 18 as marginal donors (group B). Group C included heart recipients who received a standard organ, and group D included heart recipients who received a marginal one. To analyze differences in patient character- istics among the groups, posttransplant heart survival was assessed in all groups. All data were obtained from the hospital records. Results: The mean age of the donors was 26.27±11.44 years (median age, 28 years). The marginal age showed a significant association with donor age. The age of recipients had a significant effect on survival days in the ideal group. Most patients survived for at least 1 year, with a median of 645 days in recipients from marginal donors and 689 days in re- cipients from ideal donors. Conclusions: Considering the lack of organ availability in Iran, it may be possible to use marginal donors for marginal recipients, therefore reducing the number of people on the waitlist. We also recommend establishing a national marginal donor system specifically for Iranian patients to extend the donor pool.

Effect of fiber reinforcing on instantaneous deflection of self-compacting concrete one-way slabs under early-age loading

Behnam Vakhshouri,Shami Nejadi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.2

The Early-age construction loading and changing properties of concrete, especially in the multi-story structures can affect the slab deflection, significantly. Based on previously conducted experiment on eight simply-supported one-way slabs this paper investigates the effect of concrete type, fiber type and content, loading value, cracking moment, ultimate moment and applied moment on the instantaneous deflection of Self-Compacting Concrete (SCC) slabs. Two distinct loading levels equal to 30% and 40% of the ultimate capacity of the slab section were applied on the slabs at the age of 14 days. A wide range of the existing models of the effective moment of inertia which are mainly developed for conventional concrete elements, were investigated. Comparison of the experimental deflection values with predictions of the existing models shows considerable differences between the recorded and estimated instantaneous deflection of SCC slabs. Calculated elastic deflection of slabs at the ages of 14 and 28 days were also compared with the experimental deflection of slabs. Based on sensitivity analysis of the effective parameters, a new model is proposed and verified to predict the effective moment of inertia in SCC slabs with and without fiber reinforcing under two different loading levels at the age of 14 days.

A Multi-Objective Project Scheduling Problem Subject to Project Reliability and Multi-Mode Activities with Time Window

Behnam Hosseinian Nejad,Hiwa Farughi 대한산업공학회 2021 Industrial Engineeering & Management Systems Vol.20 No.3

In this study, the necessity of considering reliability in projects and its association with other related objectives regarding project"s scheduling is investigated. In this regard, a mathematical model to optimize the objective functions, time and reliability is presented considering budget constraint, and time window for starting activities, float time and multi-mode activities following the review of the literature. Due to the great difficulty of calculations in this model, two metaheuristic algorithms, namely MOPSO and NSGAII are presented to solve the model"s problem in small, average and large scale and then several numerical samples are solved in all above mentioned scales to evaluate the algorithm performance. The results of solving the model using metaheuristic algorithms are compared in small-scale with the results of accurate problem-solving carried out by GAMS optimization software. The results indicate that both metaheuristic algorithms are able to achieve acceptable responses in short time considering all three forms of reliability function. In addition, MOPSO algorithm had the most desirable performance in achieving acceptable responses in less time and NSGAII algorithm had the most desirable performance in more extensively searching the response space.

Free vibration analysis of axially moving laminated beams with axial tension based on 1D refined theories using Carrera unified formulation

Behnam Daraei,Saeed Shojaee,Saleh Hamzehei-Javaran 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.37 No.1

In this paper, free vibration finite element analysis of axially moving laminated composite beams subjected to axial tension is studied. It is assumed that the beam has a constant axial velocity and is subject to uniform axial tension. The analysis is based on higher-order theories that have been presented by Carrera Unified Formulation (CUF). In the CUF technique, the three dimensional (3D) displacement fields are expressed as the approximation of the arbitrary order of the displacement unknowns over the cross-section. This higher-order expansion is considered in equivalent single layer (ESL) model. The governing equations of motion are obtained via Hamilton’s principle. Finally, several numerical examples are presented and the effect of the ply-angle, travelling speed and axial tension on the natural frequencies and beam stability are demonstrated.

Manipulability Based Hierarchical Control of Perturbed Walking

Behnam Miripour Fard,Mohamad Mosadeghzad 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.9

In this paper, a novel manipulability based three-level hierarchical approach is suggested for control of perturbed bipedal walking. An appropriate postural strategy is selected to restore stability if a perturbation occurs during steady-state human walking. Previous experimental studies on the human walking suggest that the selection of stabilizing strategies can be related to the kinematic manipulability of swing foot. The proposed three-level structure consists of a low, middle, and high levels. The manipulability is at the high-level layer. Therefore, in case of disturbance it determines to lengthen the step (elevating strategy) or shorten the step length (lowering strategy). The middle-level layer determines the optimal desired trajectories for joints. Finally, a low-level controller tracks the desired optimal trajectory to maintain stability. The results show the success of the manipulability based adapted control scheme against pushing perturbation. A comparison between the optimal gait patterns obtained with and without consideration of manipulability is also presented in this study. The results show that the manipulability improves disturbance rejection capability. Positioning the manipulability in the high-level of our proposed method mitigates the possibility of singularity occurrence and configuration limits during postural response.

Averaged strain energy density to assess mixed mode I/III fracture of U-notched GPPS samples

Behnam Saboori,A. R. Torabi,F. Berto,S. M. J. Razavi 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

In the present contribution, fracture resistance of U-notched GPPS members under mixed mode I/III loading conditions is assessed by using the Averaged Strain Energy Density (ASED) criterion. This criterion has been founded based on the ASED parameter averaged over a well-defined control volume embracing the notch edge. The validation of the theoretical criterion predictions is evaluated through comparing with the results of a series of mixed mode I/III fracture tests conducted on rectangular-shaped GPPS specimens weakened by a single edge U-notch. A recently developed apparatus for mixed mode I/III fracture experiments is employed for measuring the fracture loads of the specimens. The test samples are fabricated with different notch tip radii with the aim of evaluating the influence of this major feature of the U-notched components on the mixed mode I/III fracture behavior. It is shown that the onset of brittle fracture in U-notched GPPS specimens under various combinations of tension and out-of-plane shear can well be predicted by means of the ASED criterion.

Transient response analysis of tapered FRP poles with flexible joints by an efficient one-dimensional FE model

Behnam Saboori,Seyed Mohammad Reza Khalili 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.2

This research develops a finite element code for the transient dynamic analysis of tapered fiber reinforced polymer (FRP) poles with hollow circular cross-section and flexible joints used in power transmission lines. The FRP poles are modeled by tapered beam elements and their flexible joints by a rotational spring. To solve the time equations of transient dynamic analysis, precise time integration method is utilized. In order to verify the utilized formulations, a typical jointed FRP pole under step, triangular and sine pulses is analyzed by the developed finite element code and also ANSYS commercial finite element software for comparison. Thereafter, the effect of joint flexibility on its dynamic behavior is investigated. It is observed that by increasing the joint stiffness, the amplitude of the pole tip deflection history decreases, and the time of occurrence of the maximum deflection is earlier.

Self-compacting light-weight concrete; mix design and proportions

Behnam Vakhshouri,Shami Nejadi 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.1

Utilization of mineral and chemical admixtures in concrete technology has led to changes in the formulation and mix design in recent decades, which has, in turn, made the concrete stronger and more durable. Lightweight concrete is an excellent solution in terms of decreasing the dead load of the structure, while self-compacting concrete eases the pouring and removes the construction problems. Combining the advantages of lightweight concrete and self-compacting concrete is a new and interesting research topic. Considering its light weight of structure and ease of placement, self-compacting lightweight concrete may be the answer to the increasing construction requirements of slender and more heavily reinforced structural elements. Twenty one laboratory experimental investigations published on the mix proportion, density and mechanical properties of lightweight self-compacting concrete from the last 12 years are analyzed in this study. The collected information is used to investigate the mix proportions including the chemical and mineral admixtures, light weight and normal weight aggregates, fillers, cement and water. Analyzed results are presented in terms of statistical expressions. It is very helpful for future research to choose the proper components with different ratios and curing conditions to attain the desired concrete grade according to the planned application.

Oil Spill Four-Class Classification Using UAVSAR Polarimetric Data

Behnam Hassani,Mahmod Reza Sahebi,Reza Mohammadi Asiyabi 한국해양과학기술원 2020 Ocean science journal Vol.55 No.3

Oil pollution of oceans from various sources is a devastating environmental problem and immediate detection of oil spills is crucial. Remote sensing techniques have provided an unprecedented opportunity for early oil spill detection and classification with an easy, quick, and cheap approach. Moreover, Fully Polarimetric Synthetic Aperture Radar (PolSAR) data with unique capabilities and informative features is an immense data source for oil spill detection on large scales. The objective of the present study is to utilize PolSAR data not only for oil spill detection, but also to classify the detected oil spill in the ocean into four classes: thick oil, thin oil, oil/water mixture, and clear water. In this study, numerous polarimetric decomposition parameters and texture features are extracted from the PolSAR image. A two-phase feature selection method, manually selection based on oil and water surface backscattering behavior and an optimization algorithm, has been employed on the extracted features to select the optimum feature set. The selected feature set has been used to classify the PolSAR image into oil and water classes. Moreover, the high sensitivity and discriminative power of the validation PolSAR dataset, UAVSAR L-band quad-pol data, is exploited by classifying the image into four classes. Remarkable acquired classification accuracies of 90.21% and 85.41% and Kappa coefficient of 0.8052 and 0.7905 for two-class and four-class classifications, respectively, demonstrate the robustness and high potential of the proposed methodology for oil spill detection and classification.

Adsorption-induced resonance frequency shift in Timoshenko microbeams

Behnam Gheshlaghi,Seyyed M. Hasheminejad 한국물리학회 2011 Current Applied Physics Vol.11 No.4

This paper adopts a sandwich-beam model with two surface layers of finite thickness to investigate the resonance frequency shift of moderately thick microbeams due to atom/molecule adsorption in presence of surface effects. Timoshenko beam theory is employed to take into account the effects of shear deformation and rotary inertia. It is found that, in addition to surface effects, the resonance frequency could perceptively depend on adsorption-induced mass and bending stiffness variation of the microbeam which in turn depend on the adatom category and the substrate material. Adsorption and surface effects on the first three modes of vibrations are also studied, and comparisons are made with the results obtained on the basis of Euler―Bernoulli beam theory. This study is of interest for the optimal design of micro- and nanobeam-based sensors.