Numerical analysis of two and three dimensional buoyancy driven water-exit of a circular cylinder

Shahab Moshari,Amir Hossein Nikseresht,Reza Mehryar 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.2

With the development of the technology of underwater moving bodies, the need for developing the know-ledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free sur-face deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF) scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an ex-ternal force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simula-tion errors of present work (using VOF method) for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

Board Structure and Likelihood of Financial Distress: An Emerging Asian Market Perspective

Shahab UD-DIN,Muhammad Yar KHAN,Anam JAVEED,Ha PHAM 한국유통과학회 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.11

This study examines the relationship between the attributes of board structure and the likelihood of financial distress for the non-financial sector of an emerging market characterized by concentrated ownership and family-controlled business. The present study utilized panel logistic regression to estimate the relationship between board structure attributes and the likelihood of financial distress. We used Altman Z-Score as a proxy for firm financial distress, as this tool measures the financial distress inversely. The study finds a significant relationship between board size and the likelihood of financial distress. The results show that a one-unit increase in board size would decrease the probability of financial distress by 3.4%. Further, we observe that a greater level of board independence is associated with a lower likelihood of financial distress. A one-unit increase in board independence would decrease the probability of financial distress by 20.4%. We also find a significant positive impact of leverage on the likelihood of financial distress. The present study contributes to the body of literature on board structure attributes and likelihood of financial distress in emerging markets, like Pakistan. Furthermore, the findings would be beneficial for corporate policymakers and investors in formulating corporate financial strategy and predicting business failure.

Neoadjuvant chemoradiotherapy versus immediate surgery for resectable and borderline resectable pancreatic cancer: Meta-analysis and trial sequential analysis of randomized controlled trials

Shahab Hajibandeh,Shahin Hajibandeh,Christina Intrator,Karim Hassan,Mantej Sehmbhi,Jigar Shah,Eshan Mazumdar,Ambareen Kausar,Thomas Satyadas 한국간담췌외과학회 2023 Annals of hepato-biliary-pancreatic surgery Vol.27 No.1

We aimed to compare resection and survival outcomes of neoadjuvant chemoradiotherapy (CRT) and immediate surgery in patients with resectable pancreatic cancer (RPC) or borderline resectable pancreatic cancer (BRPC). In compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement standards, a systematic review of randomized controlled trials (RCTs) was conducted. Random effects modeling was applied to calculate pooled outcome data. Likelihood of type 1 or 2 errors in the meta-analysis model was assessed by trial sequential analysis. A total of 400 patients from four RCTs were included. When RPC and BRPC were analyzed together, neoadjuvant CRT resulted in a higher R0 resection rate (risk ratio [RR]: 1.55, p = 0.004), longer overall survival (mean difference [MD]: 3.75 years, p = 0.009) but lower overall resection rate (RR: 0.83, p = 0.008) compared with immediate surgery. When RPC and BRPC were analyzed separately, neoadjuvant CRT improved R0 resection rate (RR: 3.72, p = 0.004) and overall survival (MD: 6.64, p = 0.004) of patients with BRPC. However, it did not improve R0 resection rate (RR: 1.18, p = 0.13) or overall survival (MD: 0.94, p = 0.57) of patients with RPC. Neoadjuvant CRT might be beneficial for patients with BRPC, but not for patients with RPC. Nevertheless, the best available evidence does not include contemporary chemotherapy regimens. Patients with RPC and those with BRPC should not be combined in the same cohort in future studies.

Outcome of Inversion 16 in TKD Positive and Negative Acute Myeloid Leukemia Patients

Shahab, Sadaf,Zahid, Danish,Ahmed, Shariq,Nadeem, Muhammad,Farzana, Tasneem,Taj, Mehwesh,Ahmed, Nuzhat,Shamsi, Tahir S Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Chronic Infection and Nodule Formation following Deoxycholate Injection

Shahab Shahid,Fawaz Al-Hassani 대한성형외과학회 2022 Archives of Plastic Surgery Vol.49 No.3

Aqualyx (Marllor International Ltd, Rimini, Italy) was originally developed in Italy by Professor Pasquale Motolese and has been commercially available since 2009. It is a deoxycholate, aqueous gelatinous solution mixed with saline and buffering compounds. It is the only drug approved by the European Union for the reduction in localized fat. Aqualyx is sold exclusively to doctors and nurses trained in intralipotherapy. In the case of our patient, the product administered was advertised as Aqualyx, but was not administered by a trained health professional and was administered too superficially. The patient developed severe pain following the injection and was unable to sit for several weeks. There was localized skin necrosis, and palpable collections where the injection was administered. Our initial suspicion was development of an abscess or hematoma. To characterize further, we arranged an ultrasound scan that showed a “superficial hypoechoic lesion” but no deeper infection or spread. The numerous painful nodules ruptured onto the skin surface, resulting in purulent and bleeding lesions. This case demonstrates the importance of appropriate training and competence in performing cosmetic procedures including injections and fat dissolving treatments.

User pairing and power allocation for non-orthogonal multiple access: Capacity maximization under data reliability constraints

Shahab, Muhammad Basit,Shin, Soo Young ELSEVIER SCIENCE B.V., AMSTERDAM 2018 Physical communication Vol.2018 No.30

Fundamental Bounds on the Age of Information in Multi-Hop Global Status Update Networks

Shahab Farazi,Andrew G. Klein,D. Richard Brown III 한국통신학회 2019 Journal of communications and networks Vol.21 No.3

This paper studies the “age of information” in a generalmulti-source multi-hop wireless network with explicit channelcontention. Specifically, the scenario considered in this paper assumesthat each node in the network is both a source and a monitorof information, that all nodes wish to receive fresh status updatesfrom all other nodes in the network, and that only one nodecan transmit in each time slot. Lower bounds for peak and averageage of information are derived and expressed in terms offundamental graph properties including the connected dominationnumber. An algorithm to generate near-optimal periodic status updateschedules based on sequential optimal flooding is also developed. These schedules are analytically shown to exactly achieve thepeak age bound and also achieve the average age bound within anadditive gap scaling linearly with the size of the network. Moreover,the results are sufficiently general to apply to any connectednetwork topology. Illustrative numerical examples are presentedwhich serve to verify the analysis for several canonical networktopologies of arbitrary size, as well as every connected networkwith nine or fewer nodes.

Nanostructured polysaccharide-based carriers for antimicrobial peptide delivery

Shahab Mohtashamian,Soheil Boddohi 한국약제학회 2017 Journal of Pharmaceutical Investigation Vol.47 No.2

In recent decade, antimicrobial resistance is a serious international concern resulted by misuse of antibiotics. Some dangerous pathogenic strains such as Methicillin- resistant Staphylococcus aureus are resistant to the wide range of conventional antibiotics. Antimicrobial peptides (AmPs) are remarkable antibacterial drugs, which can be used instead of conventional antibiotics due to their membrane targeting activity especially against both gramnegative and gram-positive multidrug-resistant strains of pathogenic bacteria. Target delivery of AmPs is necessary because of short half-life and relative toxicity against healthy cells. Polysaccharide-based nanostructured carriers such as nanoparticles and layer-by-layer thin films are widely used due to their biocompatibility, stimuli-responsive properties, and strong affinity to bond with proteins and peptides. In this review, we focus on some prominent polysaccharide-based AmP delivery systems and describe some advantage and disadvantage of each carrier. We also introduce some novel AmP nanocarriers due to the two main strategies of combat against antibacterial resistance. Among these novel carriers, polysaccharide-based nanogels have incredible properties such as high loading capacity, stimuli responsive release behavior, simple largescale production, and thermodynamically stability, which could be a promising candidate for controlled release of AmPs.

Characterization of The Rotating Vortex Rope Pressure Oscillations in a Kaplan Model Turbine Draft Tube

Shahab Shiraghaee,Joel Sundström,Mehrdad Raisee,Michel J. Cervantes 한국유체기계학회 2023 International journal of fluid machinery and syste Vol.16 No.2

The swirling flow under the part-load (PL) operation of hydraulic turbines causes the formation of a rotating vortex rope (RVR) inside the draft tube. The RVR precession induces pressure fluctuations and periodic loadings that can jeopardize the hydraulic machine's structure and performance. The behavior of these fluctuations is closely related to the characteristics of the RVR, which can vary for different PL conditions. A series of experiments have been performed to characterize the periodic behavior and stability of the RVR under various PL operating conditions. For this purpose, wall pressure measurements were conducted at two sections along the draft tube axis of a scaled-down model of the U9 Kaplan turbine. Spectral analyses were performed, and the periodic stability of the RVR was investigated based on the statistical analyses of the amplitude and frequency of the pressure oscillations. The results showed that the amplitude of the pressure oscillations increases with the decrease of the discharge while the stability of the RVR decreases. Upstream, the behavior and stability of the RVR asynchronous mode pressure oscillations are highly dependent on the flow conditions at the draft tube entrance. However, due to the downstream RVR dissipation, the effects imposed by the elbow become the dominant factor in the RVR behavior close to the elbow. The statistical method proposed in this study provided an in-depth view of the RVR instantaneous behavior, allowing a more accurate characterization of the phenomenon than only studying its spectral content.

Molecular Involvement and Prognostic Importance of Fms-like Tyrosine Kinase 3 in Acute Myeloid Leukemia

Shahab, Sadaf,Shamsi, Tahir S.,Ahmed, Nuzhat Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

AML (Acute myeloid leukemia) is a form of blood cancer where growth of myeloid cells occurs in the bone marrow. The prognosis is poor in general for many reasons. One is the presence of leukaemia-specific recognition markers such as FLT3 (fms-like tyrosine kinase 3). Another name of FLT3 is stem cell tyrosine kinase-1 (STK1), which is known to take part in proliferation, differentiation and apoptosis of hematopoietic cells, usually being present on haemopoietic progenitor cells in the bone marrow. FLT3 act as an independent prognostic factor for AML. Although a vast literature is available about the association of FLT3 with AML there still is a need of a brief up to date overview which draw a clear picture about this association and their effect on overall survival.