36 research outputs found

    Signed graphs cospectral with the path

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    A signed graph Γ\Gamma is said to be determined by its spectrum if every signed graph with the same spectrum as Γ\Gamma is switching isomorphic with Γ\Gamma. Here it is proved that the path PnP_n, interpreted as a signed graph, is determined by its spectrum if and only if n0,1n\equiv 0, 1, or 2 (mod 4), unless n{8,13,14,17,29}n\in\{8, 13, 14, 17, 29\}, or n=3n=3

    Prediction of asphaltene precipitation upon injection of various gases at near-wellbore conditions: A simulation study using PC-SAFT EoS

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    International audienceThe depletion of oil reservoirs and increased global oil demand have given impetus to employ various secondary and tertiary oil recovery methods. Gas injection is widely used in both secondary and tertiary modes, though the major problem associated with this process is the precipitation and deposition of asphaltene, particularly at near-wellbore conditions. In-depth knowledge of asphaltene phase behavior is therefore essential for the prediction of asphaltene precipitation. Previous studies reported the impact of gas injection on asphaltene phase behavior, but the knowledge of precipitation of asphaltene as a function of different mole fractions of injected gas is also imperative. In this study, the thermodynamic model of PC-SAFT EoS is used to discern the phase equilibrium of asphaltene by analyzing the asphaltene drop-out curve during gas injection. Asphaltene drop-out curves of two different live oil samples are analyzed by injecting CO2, CH4, and N2 gases at different mole percentages and temperatures. The results revealed that PC-SAFT EoS can serve as a reliable tool for estimating bubble pressure and asphaltene onset pressure for a wide range of temperatures, pressures, and compositions. The simulation results for the injection of CO2, CH4, and N2 also showed that CO2 gas gives minimum asphaltene precipitation. It reduces the size of the drop-out curve or moves it toward higher pressures. CH4 and N2 expand the drop-out curve by raising the upper onset point. CH4 increases the maximum point of the drop-out curve for two types of oil studied (A and B) at two different temperatures. N2 raises the maximum point of oil type “A” by approximately 57% at 395 K, while it has no effect on the maximum point of oil type “B”. In addition, reducing the temperature resulted in either decrease or increase of asphaltene solubility, demonstrating that the impact of temperature on asphaltene precipitation is closely related to the composition of the crude

    On sign-symmetric signed graphs

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    A signed graph is said to be sign-symmetric if it is switching isomorphic to its negation. Bipartite signed graphs are trivially sign-symmetric. We give new constructions of non-bipartite sign-symmetric signed graphs. Sign-symmetric signed graphs have a symmetric spectrum but not the other way around. We present constructions of signed graphs with symmetric spectra which are not sign-symmetric. This, in particular answers a problem posed by Belardo, Cioabă, Koolen, and Wang (2018)

    RPL LOAD BALANCING IN INTERNET OF THINGS

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    ABSTRACT:  The wide address space provided by Internet Protocol version 6 (IPv6) lets any thing to be identified uniquely. consistency of the modified version of IPv6 protocol stack with smart objects, facilitated the Internet interconnection of the networks of smart objects and introduced Internet of things. A smart object is a small micro-electronic device that consists of a communication device, a small microprocessor and a sensor or an actuator. A network made of such devices is called low-power and lossy network. RPL routing protocol that is consistent to IPv6, is designed to be used in these kinds of networks. Load balancing is not considered in the RPL design process. Whenever RPL is used in large scale low-power and lossy networks some nodes will suffer from congestion and this problem severely degrades network performance. In this paper, we consider solutions provided to tackle RPL load balancing problems. Load balancing algorithms and protoclos are evaluated through simulation. We evaluate IETF RPL implementation and LB-RPL method with Contiki OS Java (COOJA) simulator. They are assessed comprehensively through metrics such as Packet delivery Ratio, Average End to End delay, and Gateway Throughput. LB-RPL improves RPL in terms of Packet delivery Ratio and throughput but increases Average End to End delay. Simulations results show that RPL load balancing needs extensive works to be performed yet

    IMPLEMENTING NDN USING SDN: A REVIEW ON METHODS AND APPLICATIONS

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    In recent years many claims about the limitations of todays’ network architecture, its lack of flexibility and ability to response to ongoing changes and increasing users demands. In this regard, new network architectures are proposed. Software Defined Networking (SDN) is one of these new architectures which centralizes the control of network by separating control plane from data plane. This separation leads to intelligence, flexibility and easier control in computer networks. One of the advantages of this framework is the ability to implement and test new protocols and architectures in actual networks without any concern of interruption. Named Data Networking (NDN) is another paradigm for future network architecture. With NDN the network becomes aware of the content that is providing, rather than just transferring it among end-points. NDN attracts researchers’ attention and known as the potential future of networking and internet. Providing NDN functionalities over SDN is an important requirement to enable the innovation and optimization of network resources. In this paper first we describe about SDN and NDN, and then we introduce methods for implementing NDN using SDN. We also point out the advantages and applications of implementing NDN over SDN

    Effectsof Camellia sinensis ethanolic extract on histometric and histopathological healing process of burn wound in rat

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    Green tea (Camellia sinensis) that were used as an ancient herbal drug in Asia, with having anti-oxidant and anti-inflammatory properties, may can improve wound healing process, thereforethe present study were design to determinate the effect of green tea ethanolicextract on burn wound healing process in rat. For this experimental study, 36 healthy male Wistar rats were randomly selected into three groupsof A, B and Cwhich, respectively treated with, Vaseline + 0.6 green tea extract, Vaseline andnormal salinefor a 21 days period. Burn Wounds' areas were measured and calculated by caliper every other day and pathologic samples were taken at 3rd, 12th and 21st day for histopathological examinations. In the end, all data were analyzed by SPSS 16 using survival analysis (Breslow test), repeated measured ANOVA, one-way ANOVA and Mann-Whitney. P<0.05 was considered as statistically significant.Regarding Breslow test, the mean healing duration in group A with18 days was shorter in compared to group B with 20.33 days, (P=0.023). In according to Mann-Whitney test, comparing groups A and C during the whole study, indicated no statistically significant differences in histopathologicalscoresof epithelial regeneration and angiogenesis except inflammatory cells. Green tea extract could help wound healing process, probably effective on burn wounds healing. © IDOSI Publications, 2013

    An order acceptance using FAHP and TOPSIS methods: A case study of Iranian vehicle belt production industry

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    Decisions related to acceptance or rejection of orders play an important role in companies engaged in make-to-order production. The incoming orders have a specific delivery date by which the customer expects the due date to be met and the order delivered. In some cases the level of input orders exceeds beyond the existing capacity. In such situations the main concern is to decide which orders must be accepted and which ones rejected taking into account the available production capacity. This paper prioritises the input orders according to a comprehensive and systematic multi criteria decision making (MCDM) model. It then proceeds with making decisions to either accept or reject orders according to the calculated prioritises and production constraints. Ultimately the optimum list of orders for acceptance is determined. The proposed model is a combination of two techniques of Fuzzy Analytical Hierarchy Process (FAHP) and Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS). In this model FAHP is used to determine the weights of criteria and TOPSIS is used for prioritizing the orders. Finally the proposed model is tested for its efficiency by application to a real case

    Diagnostic accuracy of circular RNA for diabetes Mellitus : a systematic review and diagnostic Meta-analysis

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    Acknowledgements: We thank all our staff at the Tehran University of medical sciences and at Kurdistan University of Medical sciences who helped us in this work. We also acknowledge the papers that we used and participants in those papers. Funding Information: The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Publisher Copyright: © 2023, The Author(s).Peer reviewedPublisher PD

    Neutrophil-Lymphocyte Ratio in Different Stages of Breast Cancer

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    Despite many advances in the treatment of breast cancer, it is still the second most common cause of death in women in the United States. It has been shown that inflammation plays a major role in the treatment of these cancers and inflammatory factors enhance tumor growth, invasion, metastasis, and vascularization. In this study, we would like to analyze peripheral blood neutrophil-lymphocyte ratio (NLR) in breast cancer patients and its correlation with disease staging. This cross-sectional analytic study was conducted in Imam Hospital, affiliated with Tehran University of Medical Sciences; a total of 195 female patients with breast cancer met the inclusion criteria. All of the patients had a complete blood count with leukocyte differential performed before chemotherapy. Medical records including pathology reports were also available. Data for all patients were collected prior to any surgical intervention. Exclusion criteria included clinical evidence of active infection, presence of hematological disorders, acute as well as chronic inflammatory or autoimmune diseases, or prior steroid therapy. Higher platelet count was significantly associated with the higher stage. The stage was not associated with the hemoglobin level. There was no association between the tumor size and age of patients with NLR. There was a significant relationship between NLR and IDC. There was a significant relationship between IDC and NLRs of less than 8.1 and greater than 3.3. There was a significant relationship between NLR and vascular invasion. There was no association between NLR and estrogen receptor and HER2. There was no significant relationship between the PLR and the cancer stage. In this study, NLR showed a significant relation with the disease staging. As the NLR increases the stage increases as well. Therefore, this ratio may be helpful in the preoperative evaluation of patients with breast cancer
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