Flexural Integrity Between the Individual Channels of Built-Up Cold-Formed Steel Beams

Mir Basar Suhaib,Manzoor Ahmad Tantray 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

This paper investigates the influence of commonly used screw connections on the integrity of built-up beams formed by connecting two lipped channel sections in a back-to-back configuration. An experimental investigation on the behaviour of 6 built-up CFS beams connected by self-drilling screws is presented in this paper. The screw spacing was varied along the length as well as the depth of the beams. The test results indicate that the screw spacing has some influence on the capacity of the built-up beams. An increase in screw spacing leads to an undesirable separation of channels and thus has a negative impact on the composite action between the members. Finite element models were developed and after successful validation, a parametric study involving 124 models was carried out, to investigate the impact of larger longitudinal screw spacings on the integral behaviour of the beams. It was observed that the flexural capacity decreased by 11%, 14%, 17% and 19% when the longitudinal distance between the screws increased from 50 to 1050 mm for beams with web depths 150 mm, 200 mm, 250 mm and 300 mm respectively. It can be concluded that flexural capacity is directly proportional to the decrease in the screw spacing and increase in the number of screw rows. The results also indicate that the percentage decrease in strength is greater for beams with larger web depths. An idealized cross section assuming complete composite action was simulated for each web depth using FE modelling and the capacities of all the screw-connected “semi-rigid” beams were compared against it. The capacity of screw connected built-up beams with web depths 150 mm, 200 mm, 250 mm and 300 mm was found to be 0.71, 0.64, 0.61 and 0.59 times that of the idealized cross-section on average, respectively. The moment capacities of screw-connected beams were also compared against the theoretical values obtained from AISI S-100. It was observed that the design guidelines provided in AISI S-100 were unable to account for the reduction in the moment capacity due to the screw connection in built-up members. AISI S-100 is conservative by as much as 34%, 42%, 46% and 48% for beams with web depths 150 mm, 200 mm, 250 mm and 300 mm respectively.

Behaviour of GFRP Stiffened Cold-Formed Steel Built-up Beams

Mir Basar Suhaib,M. A. Tantray 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4

This article explores a novel approach to inhibit local premature failures in cold-formed steel (CFS) beams and enhance their fl exural capacity by introducing external web stiff eners to buckling prone regions. An experimental and fi nite element investigation on the behaviour of doubly symmetric CFS built-up channel beams with adhesively bonded glass-fi ber reinforced polymer (GFRP) stiff eners is presented in this paper. Unlike previous attempts, where fl at plates have been used, the results of pultruded T-shaped GFRP stiff eners on the fl exural capacity and local failure inhibition of the CFS beams are presented. The viability of suggested strengthening arrangement is assessed by comparing the results from CFS beams strengthened with steel stiff eners of equivalent stiff ness. One control and six reinforced beams, stiff ened with diff erent confi gurations of both steel and GFRP stiff eners in the moment span, were tested up to failure under four-point bending. The change in the mode of failure from buckling at discrete regions to global failures with an improvement in the fl exural capacity by up to 39% was achieved using adhesively bonded external stiff eners in the present study. It can be concluded that adhesively bonded GFRP stiff eners provide a cost-eff ective and adequate alternative to enhance the fl exural performance and inhibit the local failures in thin-walled beams. Finite element models were developed and verifi ed against test results. FE models were found to be capable of predicting the ultimate capacity and failure of stiff ened beams with fair accuracy.

Mathematical Models for the Biofilm Formation of Geobacillus and Anoxybacillus on Stainless Steel Surface in Whole Milk

Karaca, Basar,Buzrul, Sencer,Cihan, Arzu Coleri Korean Society for Food Science of Animal Resource 2021 한국축산식품학회지 Vol.41 No.2

Biofilm formation of Geobacillus thermodenitrificans, Geobacillus thermoglucosidans and Anoxybacillus flavithermus in milk on stainless steel were monitored at 55℃, 60℃, and 65℃ for various incubation times. Although species of Geobacillus showed a rapid response and produced biofilm within 4 h on stainless steel, a delay (lag time) was observed for Anoxybacillus. A hyperbolic equation and a hyperbolic equation with lag could be used to describe the biofilm formation of Geobacillus and Anoxybacillus, respectively. The highest biofilm formation amount was obtained at 60℃ for both Geobacillus and Anoxybacillus. However, the biofilm formation rates indicated that the lowest rates of formation were obtained at 60℃ for Geobacillus. Moreover, biofilm formation rates of G. thermodenitrificans (1.2-1.6 Log10CFU/mL∙h) were higher than G. thermoglucosidans (0.4-0.7 Log10CFU/mL∙h). Although A. flavithermus had the highest formation rate values (2.7-3.6 Log10CFU/mL∙h), this was attained after the lag period (4 or 5 h). This study revealed that modeling could be used to describe the biofilm formation of thermophilic bacilli in milk.

[튀르키예] 왜 미니멀리즘인가?

케말 바사르(Kemal Basar) 한국연극협회 2023 한국연극 Vol.2023 No.7

On Some Spaces Isomorphic to the Space of Absolutely q-summable Double Sequences

Capan, Husamettin,Basar, Feyzi Department of Mathematics 2018 Kyungpook mathematical journal Vol.58 No.2

Let 0 < q < ${\infty}$. In this study, we introduce the spaces ${\mathcal{BV}}_q$ and ${\mathcal{LS}}_q$ of q-bounded variation double sequences and q-summable double series as the domain of four-dimensional backward difference matrix ${\Delta}$ and summation matrix S in the space ${\mathcal{L}}_q$ of absolutely q-summable double sequences, respectively. Also, we determine their ${\alpha}$- and ${\beta}-duals$ and give the characterizations of some classes of four-dimensional matrix transformations in the case 0 < q ${\leq}$ 1.

Risk-sensitive Control of Markov Jump Linear Systems: Caveats and Difficulties

문준,Tamer Basar 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.1

In this technical note, we revisit the risk-sensitive optimal control problem for Markov jump linearsystems (MJLSs). We first demonstrate the inherent difficulty in solving the risk-sensitive optimal control problemeven if the system is linear and the cost function is quadratic. This is due to the nonlinear nature of the coupledset of Hamilton-Jacobi-Bellman (HJB) equations, stemming from the presence of the jump process. It thus followsthat the standard quadratic form of the value function with a set of coupled Riccati differential equations cannot bea candidate solution to the coupled HJB equations. We subsequently show that there is no equivalence relationshipbetween the problems of risk-sensitive control and H¥ control of MJLSs, which are shown to be equivalent in theabsence of any jumps. Finally, we show that there does not exist a large deviation limit as well as a risk-neutral limitof the risk-sensitive optimal control problem due to the presence of a nonlinear coupling term in the HJB equations.

Antimicrobial Resistance of Enterococcus Species Isolated from Chicken in Turkey

Pınar Sanlibaba,Basar Uymaz Tezel,Esra Senturk 한국축산식품학회 2018 한국축산식품학회지 Vol.38 No.2

The aim of the present work was to provide information about Enterococcus strains isolated from pre-packaged chicken samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. We report the first study on the occurrence of antibiotic resistant enterococci in pre-packaged chicken samples in Ankara. A total of 97suspiciousenterococcal isolates were identified from 122 chicken samples. All isolates were identified to species level by phenotypic and molecular methods. In the 16S rDNA sequence analysis, Enterococcus faecium (61.85%) and Enterococcus faecalis(38.15%) were found to be the most frequently detected Enterococcus spp. Of the 97 isolates tested for hemolytic activity, 12.37% enterococcal strains were β-hemolytic. β-Hemolysin was most prevalent among E. faecium(58.33%) compared to E. faecalis(41.66%). Disk diffusion method was used for determining ofantibiotic resistance. The analysis of the antimicrobial resistance of the 97 Enterococcus isolates revealed that the resistance to kanamycin (98.96%), rifampicin (80.41%) and ampicillin (60.82%) was most frequent. Furthermore, resistance to erythromycin (38.14%) and ciprofloxacin (34.02%) was also observed. The frequencies of resistance to tetracycline (9.27%), penicillin G (8.24%), and chloramphenicol (3.09%), gentamicin (2.06%) and streptomycin (1.03%) were low. None of the isolates was resistant to vancomycin. Multi-drug resistance was found in 97.93% of Enterococcus strains. E. faecium strains showed a more resistant phenotype than E. faecalis strains according to the antibiotic resistance levels. The results of this study indicated that chicken meat is a potential reservoir for the transmission of antibiotic resistance from animals to humans.

Linear Quadratic Risk-Sensitive and Robust Mean Field Games

Moon, Jun,Basar, Tamer IEEE 2017 IEEE transactions on automatic control Vol.62 No.3

<P>This paper considers two classes of large population stochastic differential games connected to optimal and robust decentralized control of large-scale multiagent systems. The first problem (P1) is one where each agent minimizes an exponentiated cost function, capturing risk-sensitive behavior, whereas in the second problem (P2) each agent minimizes a worst-case risk-neutral cost function, where the 'worst case' stems from the presence of an adversary entering each agent's dynamics characterized by a stochastic differential equation. In both problems, the individual agents are coupled through the mean field term included in each agent's cost function, which captures the average or mass behavior of the agents. We solve both P1 and P2 via mean field game theory. Specifically, we first solve a generic risk-sensitive optimal control problem and a generic stochastic zero-sum differential game, where the corresponding optimal controllers are applied by each agent to construct the mean field systems of P1 and P2. We then characterize an approximated mass behavior effect on an individual agent via a fixed-point analysis of the mean field system. For each problem, P1 and P2, we show that the approximated mass behavior is in fact the best estimate of the actual mass behavior in various senses as the population size, N, goes to infinity. Moreover, we show that for finite N, there exist is an element of-Nash equilibria for both P1 and P2, where the corresponding individual Nash strategies are decentralized in terms of local state information and the approximated mass behavior. We also show that is an element of can be taken to be arbitrarily small whenN is sufficiently large. We show that the is an element of-Nashequilibria of P1 and P2 are partially equivalent in the sense that the individual Nash strategies share identical control laws, but the approximated mass behaviors for P1 and P2 are different, since in P2, the mass behavior is also affected by the associated worst-case disturbance. Finally, we prove that the Nash equilibria for P1 and P2 both feature robustness, and as the parameter characterizing this robustness becomes infinite, the two Nash equilibria become identical and equivalent to that of the risk-neutral case, as in the one-agent risk-sensitive and robust control theory.</P>

Multi-modality Imaging of Cocaine-induced Rupture of Sinus of Valsalva Aneurysm Communicating with Tricuspid Valve Annulus

Kianoush Ansari-Gilani,Basar Sareyyupoglu,Robert C Gilkeson 한국심초음파학회 2020 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.28 No.3

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GENERALIZED((ξ, ζ)-) SOFT INTERIOR Γ-HYPERIDEALS OF Γ-SEMIHYPERGROUPS

Abbasi, M.Y.,Basar, A.,Talee, A.F.,Khan, S.A. The Honam Mathematical Society 2018 호남수학학술지 Vol.40 No.1

In this paper, we introduce the notion of ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals of ${\Gamma}$-semihypergroups by a new approach called soft intersection (briefly, S. I.). It is proved that in regular ${\Gamma}$-semihypergroups the ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and the ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals coincide. Further, we introduce the concept of ($\xi$, ${\zeta}$)-soft simple ${\Gamma}$-semihypergroup and characterize the simple ${\Gamma}$-semihypergroups in terms of ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals.