Patterned and Disordered Continuous Abelian Sandpile Model

We study critical properties of the continuous Abelian sandpile model with anisotropies in toppling rules that produce ordered patterns on it. Also we consider the continuous directed sandpile model perturbed by a weak quenched randomness and study critical behavior of the model using perturbative conformal field theory and show the model has a new random fixed point.Comment: 11 Pages, 6 figure

Higher Order and boundary Scaling Fields in the Abelian Sandpile Model

The Abelian Sandpile Model (ASM) is a paradigm of self-organized criticality (SOC) which is related to $c=-2$ conformal field theory. The conformal fields corresponding to some height clusters have been suggested before. Here we derive the first corrections to such fields, in a field theoretical approach, when the lattice parameter is non-vanishing and consider them in the presence of a boundary.Comment: 7 pages, no figure

Computed Tomographic measurement of distal femor rotation in Iranian population

Background: Proper rotation of components in total knee arthroplasty (TKA) will largely affect the postoperative outcome. Ethnical variation may affect rotational profile. We aimed to evaluate distal femur rotation in Iranian population using transepicondylar axes. Methods: From a total of 450 knee CT scans and via consecutive sampling, 150 qualified subjects with normal lower extremities alignment were selected comprising 96 (64) males and 54 (36) females aging 17-80 years. The posterior condylar angle and condylar twist angles were defined as angles between either surgical epicondylar axis (line connecting lateral epicondylar prominence and the medial sulcus) or clinical epicondylar axis (line connecting most prominent points of both epicondyle) and posterior conylar line. Data were compared among genders. Results: Average age of our samples was 43 years (ranging 11-80). Mean (±sd) values for posterior condylar angle and condylar twist angles were 2.35° (±1.34) and 5.77° (±1.70), respectively. The former variable was not discernible in twenty of our subjects because of obscure medial sulcus. Our findings were totally appeared similar to studies from other ethnicities and the observed minor differences may have originated from amount of osteoarthritis and malalignment. Conclusion: Overall, Iranian distal femur rotational profile was similar to other reports. Some minor observed differences may be partially due to samples' age and different amount of knee osteoarthritis. It is proposed to rely on several methods for determining rotational profile while performing TKA. Moreover, preoperative computed tomography should be fully scrutinized especially in severely osteoarthitic knees

Jordan derivations on certain Banach algebras

In this paper, we study the types of Jordan derivations of a Banach algebra $A$ with a right identity $e$. We show that if $eA$ is commutative and semisimple, then every Jordan derivation of $A$ is a derivation. In this case, Jordan derivations map $A$ into the radical of $A$. We also prove that every Jordan triple left (right) derivation of $A$ is a Jordan left (right) derivation. Finally, we investigate the range of Jordan left derivations and establish that every Jordan left derivation of $A$ maps $A$ into $eA$

Parameters of lower extremities alignment view in Iranian adult population

Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 ± 1.2º. The Knee joint was shown to be medially inclined 3.6 ± 1.7º in men comparing 2 ± 2º of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 ± 1.6º. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery

Morphology of proximal tibia in iranian population and its correlation with available prostheses

Background: Total knee arthroplasty is a complex procedure aiming to relieve pain and improve function. It is critical to select prosthesis that best cover the bone surfaces. Ethnicity may affect fitness of the components mainly designed for Caucasian populations. This study aimed to evaluate morphometric features of proximal tibia in Iranian population. Methods: During 2013, 150 consecutive patients (96 males and 54 females) form orthopedics department of Rasoul-Akram hospital with knee CT scan were randomly enrolled. We entered cases with apparent normal extremity alignment and bone maturity. Cases with history of fracture or conditions affecting knee profile were excluded. Standard cuts were simulated on CT scan. Anteroposterior (AP), mediolateral (ML) and aspect ratio (ML/AP) were measured for general morphology. Medial and lateral AP distance of tibia and their distance to tibial center were measured for checking symmetry. Results: Mean age was 43.0± 10.4 years (rang 11-80). Males showed significantly larger values in ML dimension and aspect ratio than females under a given AP value (p<0.001). However, the aspect ratio was suggestive of similar configuration of proximal tibia profiles among genders. Totally, close correlations were observed among simulated cuts and size-matched tibial components of the prostheses. However, better coverage was provided by some brands via designing interchangeable components for a given dimension. Medial and lateral condyles of tibia were almost symmetrical. Conclusion: Our findings indicated that some alterations in the shape of the components are needed to provide optimal coverage in Iranian population. We propose symmetrical configuration in designing tibial components as well

Parameters of lower extremities alignment view in Iranian adult population

Normal axial alignment restoration in lower extremities is crucial for surgeons performing reconstructive surgeries. Since reference normal values of axial alignment are affected by age, sex, and ethical issues, we tried to scrutinize these parameters in Iranian adults and compare them with normal values in literatures. Through a cross-sectional design, standing axial alignment views of lower extremities were surveyed from 100 volunteers (50 males and 50 females) aged between 15-32 years. The lower extremities alignment variables were evaluated during two separate measurements. Total average values were used for comparison among genders. Tibiofemoral mechanical angle depicted mean varus of 1.5 degrees in an Iranian population that was significantly higher in male participants. The Mean angle between anatomical and mechanical axes of the femur was 5.7 ± 1.2º. The Knee joint was shown to be medially inclined 3.6 ± 1.7º in men comparing 2 ± 2º of women with a significant difference. Joint line congruence angle was medially inclined in all of the study participants with a mean of 1 ± 1.6º. To compare with anthropometric studies of western populations, Iranian participants had more varus lower limb alignment. It seemed mainly because of larger medially inclined knee joint (knee-joint obliquity). This finding along with more compensatory ankle valgus is similar to results of other Asian studies. Such racial variation should be considered in designing appropriate systems in reconstructive surgery. © 2015 Tehran University of Medical Sciences. All rights reserved

Interaction between multiple bubbles in microchannel flow boiling and the effects on heat transfer

Flow boiling in microchannels have widely been studied in order to design more efficient cooling systems with numerical simulations forming a crucial part to deal with the areas that cannot be investigated experimentally. Previously published research largely focussed on the behaviour of a single bubble. Here, we focus on the behaviour of multiple bubbles. In this study, the influence of the distance between the bubbles (liquid slug length) is investigated in both an axisymmetric and a planar domain for two and three bubbles present. In this regard, an interface-tracking adaptive mesh refinement model was implemented to improve simulation time. Results show that the heat transfer was improved with sequential bubbles, and a 50% increase in heat transfer coefficient was observed for the cases investigated with three bubbles present. The heat transfer also improved the closer the bubbles were together.ThermaSMART Project of the European Commission, the Edinburgh Compute & Data Facility (ECDF) and Centre for High Performance Computing (CHPC), South Africa.https://www.elsevier.com/locate/ichmt2023-10-22hj2022Mechanical and Aeronautical Engineerin

Adaptive mesh refinement method for the reduction of computational costs while simulating slug flow

Microchannel flow boiling has been the focus of many experimental and numerical investigations due to the high heat transfer coefficients that it can induce. However, experimental research has been limited due to the small scales involved, leading researchers to employ computational fluid dynamics (CFD) simulations to resolve the dearth of research on microchannel flow boiling. Conventional CFD methods use a fine uniform mesh to capture the small scales and gradients, such as the liquid-vapour interface. This method has a large computational cost, and as a result, most research reported in the literature has been limited to two-dimensional axisymmetric domains. An interface-tracking adaptive mesh refinement model was created in this study to overcome the limitation of high computational costs without losing accuracy. This model dynamically refined the mesh only in the regions of interest and allowed a coarser mesh in the rest of the domain. This novel approach was able to recreate previously published results with a maximum error of 6.7%, while using less than 1.6% of the mesh elements. Several simulations were conducted in ANSYS Fluent 19.1 to determine the optimal settings for this new method to maintain accuracy and reduce cell count. These settings were determined as three levels of refinement (δL = 3), four refined cells on either side of the interface (δM = 4), and was implemented every five time steps (δT = 5). Finally, a case study was conducted to illustrate the possibility of simulating two-phase flow in microchannels in three dimensions with this method.ThermaSMART project of the European Commission, the Edinburgh Compute & Data Facility (ECDF) and the Centre for High Performance Computing (CHPC), South Africa.https://www.elsevier.com/locate/ichmt2023-10-23hj2022Mechanical and Aeronautical Engineerin