SmoothFlood: decreasing redundant messages and increasing search quality of service in peer-to-peer networks

Flooding search is a basic searching scheme for unstructured peer-to-peer networks. This technique produces exponentially redundant messages in each hop. Subsequent growths of redundant messages will limit system scalability and will cause unnecessary traffic in network areas. To improve this searching scheme and reduce redundant messages, this paper proposed a novel algorithm (SmoothFlood) which divides flooding scheme into two stages. In first stage algorithm follows standard flooding by the limited number of hops, but in the next stage it will choose nosy nodes in each region. These nodes maintain the data index of all clients’ nodes. This proposed algorithm extends the search quality by reducing redundant messages in each hop. Simulation results show it will decrease more than 65 percentages of redundant messages and will save up to 70 percentages of searching traffic

Comparison of the effect of ball and bar attachment designs on retention and stability of mandibular implant-supported overdentures

Objectives The present study evaluated the effect of bar and ball attachment designs on retention and stability of a mandibular overdenture supported by four implants.Methods An edentulous mandibular acrylic resin model with four implants in the anterior part of the ridge (A, B, D and E) was fabricated. A metal framework simulating the overdenture was also fabricated. Totally, 30 overdentures were divided into three groups based on the attachment design; BL: Four ball attachments in A, B, D and E positions; BB: One bar attachment between B and D positions and two ball attachments at positions A and E; BR: Bar attachments between the positions A, B, D and E with two posterior extensions. To evaluate the retention and stability of the overdenture, tensile dislodging forces were applied in three directions of vertical, oblique and anterior- posterior by a universal testing machine. One-way ANOVA and Tukey’s HSD test were performed to analyze the data. All tests were carried out at 0.05 level of significance.Results There were statistically significant differences between the groups in the peak load (P < 0.001). The peak load values for vertical, oblique and anterior-posterior dislodging forces were the highest for BL with 49.38 ± 2.19 N, 52.19 ± 1.44 N, and 49.03 ± 5.89 N, respectively, while these values were the lowest for BR with 29.78 ± 2.52 N, 12.10 ± 0.45 N, and 6.26 ± 0.45 N, respectively.Conclusion The attachment designs affected the retention and stability of mandibular implant-supported overdentures

Resistencia a la flexión del poliéter éter cetona poliéter de alto rendimiento en comparación con la aleación de metal base y la cerámica de circonio.

Optimal flexural strength is a critical prerequisite for prosthetic frameworks. This study aimed to assess the flexural strength of polyether ether ketone (PEEK) polymer compared to a base metal alloy and high-strength Zirconia ceramic commonly used in prosthodontic treatments. Materials and Methods: In this in vitro, experimental study, 10 bar-shaped samples measuring 18×5×2mm were fabricated of each the PEEK polymer, nickel-chromium base metal alloy and zirconia ceramic. Half of the samples in each group were subjected to 5000 thermal cycles between 5°C - 55°C with 20 seconds of dwell time and 20 seconds of transfer time to simulate oral conditions. All samples then underwent three-point bending test. Two-way ANOVA followed by Tukey’s test were applied to compare the mean flexural strength of the groups with and without thermocycling at 0.05 level of significance. Results: The flexural strength of base metal alloy, Zirconia and PEEK was 1387.70±45.50 MPa, 895.13±13.99 MPa and 192.10±5.37 MPa, respectively. The difference was significant among the groups (p<0.001). Thermocycling had no significant effect on the flexural strength of samples in any group (p=0.306). Conclusion: PEEK high-performance polymer had a lower flexural strength than base metal alloy and Zirconia ceramic, and its flexural strength was not affected by thermocycling. PEEK seems to be able to resist masticatory forces in the oral cavity pending further in vitro and clinical studies.La resistencia a la flexión óptima es un requisito previo crítico para los marcos protésicos. Este estudio tuvo como objetivo evaluar la resistencia a la flexión del polímero de poliéter éter cetona (PEEK) en comparación con una aleación de metal base y cerámica de Zirconia de alta resistencia comúnmente utilizada en tratamientos de prostodoncia. Materiales and Métodos: En este estudio experimental in vitro, se fabricaron 10 muestras en forma de barra de 18 × 5 × 2mm de cada polímero PEEK, aleación de metal base de níquel-cromo y cerámica de circonio. La mitad de las muestras en cada grupo fueron sometidas a 5000 ciclos térmicos entre 5°C - 55°C con 20 segundos de tiempo de permanencia y 20 segundos de tiempo de transferencia para simular condiciones orales. Todas las muestras se sometieron a una prueba de flexión de tres puntos. Se aplicó ANOVA bidireccional seguido de la prueba de Tukey para comparar la resistencia a la flexión media de los grupos con y sin termociclado a un nivel de significancia de 0.05. Resultados: La resistencia a la flexión de la aleación de metal base, Zirconia y PEEK fue de 1387,70 ± 45,50 MPa; 895,13 ± 13,99 MPa y 192.10 ± 5,37 MPa, respectivamente. La diferencia fue significativa entre los grupos (p<0,001). El termociclado no tuvo un efecto significativo sobre la resistencia a la flexión de las muestras en ningún grupo (p=0,306).Conclusión: El polímero de alto rendimiento PEEK tiene una resistencia a la flexión más baja que la aleación de metal base y la cerámica de circonio, y su resistencia a la flexión no se vio afectada por el termociclado. PEEK parece ser capaz de resistir las fuerzas masticatorias en la cavidad oral, con la necesidad de más estudios in vitro y clínicos

A method to improve transparency of electronic election process without identification

Transparency of bank accounts, nowadays, is an undeniable necessity, but no one denies that definite transparency throughout election process is not realized thus far in the world. This calls for fundamental changes in traditional electronic election methods. The new method must close the way for any complaints by the candidate as to the voting process as the public completely trusts in the voting mechanism. Synchronizing voting and votes counting improves the public's trust in the results of election. The proposed secure room-corridor of electronic voting employs election watchers and reports real time results of election along with observance of confidentiality of the votes. © 2015 The Authors

Shortcoming, problems and analytical comparison for flooding-based search techniques in unstructured P2P networks.

Peer-to-Peer networks attracted a significant amount of interest because of their capacity for resource sharing and content distribution. Content distribution applications allow personal computers to function in a coordinated manner as a distributed storage medium by contributing, searching, and obtaining digital content. Searching in unstructured P2P networks is an important problem, which has received considerable research attention. Acceptable searching techniques must provide large coverage rate, low traffic load, and optimum latency. This paper reviews flooding-based search techniques in unstructured P2P networks. It then analytically compares their coverage rate, and traffic overloads. Our simulation experiments have validated analytical results

Resource discovery for distributed computing systems: A comprehensive survey

Large-scale distributed computing environments provide a vast amount of heterogeneous computing resources from different sources for resource sharing and distributed computing. Discovering appropriate resources in such environments is a challenge which involves several different subjects. In this paper, we provide an investigation on the current state of resource discovery protocols, mechanisms, and platforms for large-scale distributed environments, focusing on the design aspects. We classify all related aspects, general steps, and requirements to construct a novel resource discovery solution in three categories consisting of structures, methods, and issues. Accordingly, we review the literature, analyzing various aspects for each category

Hybridflood algorithms minimizing redundant messages and maximizing efficiency of search in unstructured P2P networks

Unstructured peer-to-peer (P2P) networks, aggregate the slack resources on each peer, which may include bandwidth, storage space, and computing power. As a peer joins this P2P network, the total demand and total capacity of the system simultaneously increase. However, in a typical client-server network, as a client joins the network it only shares its demands, not its resources. Thus as more clients join the client-server network fewer resources are available to serve each client. Besides, the decentralized structure of a P2P network increases its robustness because it removes the single point of failure that can be inherent in a client-server based system. Therefore the unstructured model of the P2P network has attracted the greatest attention from both users and the researcher communities. Searching is an essential and basic activity for all P2P applications. Thus, there are a large number of research works have focused on unstructured P2P search facilities. There are two main reasons driving the research interest in this arFirst, the upward trend of digital information production, such as HTML, music and image files, requires a scalable information infrastructure that is capable of indexing and searching. Recent studies have shown that more than 97% of information produced worldwide is in a digital form. The amount of digital information is expected to grow exponentially. There are many challenges posed by such a huge amount of information for existing search systems. Second, compared to traditional centralized networks, unstructured P2P networks are particularly attractive and promising due to their scalability, availability, low cost, easy deployment, and data freshness. Meanwhile the fundamental property of existing and scalable unstructured P2P networks is the high heterogeneity of the peers that participate in the network. The heterogeneity of peers in unstructured P2Ps introduces both challenges and opportunities when designing a P2P network. Flooding is a basic file search procedure in unstructured P2P file-sharing systems. In fooding a peer initiates the file search operation by broadcasting a query to its neighbors, who continue to propagate it to their neighbors. Flooding has no knowledge about network topology nor files or resources distribution, so it ofers an attractive method for file discovery in dynamic and developing networks. In the meantime, fooding produces exponentially redundant messages at each hop. Consequently, the growth of redundant messages limits the system's scalability and causes unnecessary trafic in networks. In this thesis, we combine two search techniques to tackle this issue and improve P2P search performance in terms of search efficiency and the quality of the search results. We proposed two novel search algorithms named QuickFlood and HybridFlood. QuickFlood combines two food-based searches; fooding and teeming. QuickFlood is performed in two steps, in a first step the algorithm performs fooding in a limited number of hops. In the second step the algorithm follows a teeming search. QuickFlood compared with blocking expanding ring search decreased redundant messages by 70%, increased two-time success rate and decreased latency by 30%. Therefore, the algorithm enhanced unstructured P2P search by increasing scalability, efficiency and reliability of search. HybridFlood is also performed in two steps. The first step performs fooding with a limited number of hops. In the second step, nosey nodes are selected in each searching horizon. The nosey nodes are nodes which have the most links to other nodes. These nodes maintain the data index of all client nodes. HybridFlood in comparison to the blocking expanding ring search decreased redundant messages by 80%, increased the success rate by 2.5, and decreased of latency by 80%. In the other word the algorithm improved unstructured P2P search's scalability, efficiency and reliability. We provided analytical studies for fooding, QuickFlood and HybridFlood. The analytical results provided the best hop threshold point for the optimum growth rate coverage and redundant messages from the three systems. It also proved that in HybridFlood, broadcasting messages are reduced by at least an order of magnitude. Thus, the proposed algorithms enhance the performance of the search by reducing redundant messages, increasing the success rate and decreasing latency. The simulation experiments validated the analytical results

An Investigation on the Stack Vibrations and Geotechnical Rehabilitation Solutions Case-Study: Khangiran Gas Refinery

The 75 (m) high stacks of the sulfur recovery units of Khangiran Gas Refinery in Iran exhibited significant levels of vibration in winds. Field observations reported that vibration occurred in the stacks 9 times during reel years. The longest vibration duration is 8 hours and maximum tip deflection is 1 (m). In most intensive vibration occurrence much amount of water exits from around of foundation and some crack is created in the structure. Stack diameter is 4.57 (m) at the bottom and 3.43 (m) at the top and its total weight is 182.3 (Ton). The octagonal foundation diameter is 14 (m) at the beneath part and 6 (m) at the upper part. The thickness foundation is 0.9 (m) in beneath part and 2 (m) in upper part. Foundation base soil is layered compacted and due to special geotechnical condition, it is saturated during the years. The paper aim is review of applied geotechnical solutions such as improvement of the soil characteristics by eliminating saturation condition and foundation hardness improvement and changing natural frequency of foundation and stack by changing the mass of them. Also, the other popular solutions are discussed in the paper and finally, effectiveness of applied method is studied

Rapid Detection of Pseudomonas Aeruginosa by PCR Method Using Specific Primers of Quorum Sensing LasI gene

Abstract Background & aim: Pseudomonas aeruginosa is an opportunistic nosocomial pathogen that due to having intrinsic and acquired resistance to common antibiotics, mortality due to infections is very common. Therefore, early and accurate identification of bacteria could be effective in controlling infections and deaths. The aim of this study was to evaluate the use of a rapid method with high sensitivity and specificity based on polymerase chain reaction using gene-specific primers quorum sensing LasI system for detection of bacteria. Methods: In this study, the comparison between the results of culture and PCR for the diagnosis of Pseudomonas aeruginosa in clinical samples and other bacterial species were carried out. 40 strains of Pseudomonas aeruginosa from isolated clinical specimens were identified and confirmed by biochemical tests. LasI gene specific primers were designed using bioinformatics analysis. Sequence of this gene was amplified techniques after extraction of bacterial genome. The specificity of PCR tests with DNA from of different species, Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli and Vibrio cholerae were evaluated. A different dilution of the bacterial genome of Pseudomonas aeruginosa was used in PCR to evaluate the sensitivity of primer. Data were analyzed by t-test Results: The results indicated that the PCR test result was positive for all strains of P. aeruginosa isolates however, PCR test results were negative for the four other bacteria. Even at 10-5 Pseudomonas aeruginosa genome concentration, PCR test was positive for all isolated strains Conclusion: This study showed that the primers designed for detection of Pseudomonas aeruginosa using PCR, had higher sensitivity and specificity compared to previous methods. Keywords: Pseudomonas aeruginosa, PCR, Quorum sensing, Las

Flexural strength of polyether ether ketone high-performance polyether in comparison with base metal alloy and Zirconia ceramic

Optimal flexural strength is a critical prerequisite for prosthetic frameworks. This study aimed to assess the flexural strength of polyether ether ketone (PEEK) polymer compared to a base metal alloy and high-strength Zirconia ceramic commonly used in prosthodontic treatments. Materials and Methods: In this in vitro, experimental study, 10 bar-shaped samples measuring 18×5×2mm were fabricated of each the PEEK polymer, nickel-chromium base metal alloy and zirconia ceramic. Half of the samples in each group were subjected to 5000 thermal cycles between 5°C - 55°C with 20 seconds of dwell time and 20 seconds of transfer time to simulate oral conditions. All samples then underwent three-point bending test. Two-way ANOVA followed by Tukey’s test were applied to compare the mean flexural strength of the groups with and without thermocycling at 0.05 level of significance. Results: The flexural strength of base metal alloy, Zirconia and PEEK was 1387.70±45.50 MPa, 895.13±13.99 MPa and 192.10±5.37 MPa, respectively. The difference was significant among the groups (p<0.001). Thermocycling had no significant effect on the flexural strength of samples in any group (p=0.306). Conclusion: PEEK high-performance polymer had a lower flexural strength than base metal alloy and Zirconia ceramic, and its flexural strength was not affected by thermocycling. PEEK seems to be able to resist masticatory forces in the oral cavity pending further in vitro and clinical studies.La resistencia a la flexión óptima es un requisito previo crítico para los marcos protésicos. Este estudio tuvo como objetivo evaluar la resistencia a la flexión del polímero de poliéter éter cetona (PEEK) en comparación con una aleación de metal base y cerámica de Zirconia de alta resistencia comúnmente utilizada en tratamientos de prostodoncia. Materiales and Métodos: En este estudio experimental in vitro, se fabricaron 10 muestras en forma de barra de 18 × 5 × 2mm de cada polímero PEEK, aleación de metal base de níquel-cromo y cerámica de circonio. La mitad de las muestras en cada grupo fueron sometidas a 5000 ciclos térmicos entre 5°C - 55°C con 20 segundos de tiempo de permanencia y 20 segundos de tiempo de transferencia para simular condiciones orales. Todas las muestras se sometieron a una prueba de flexión de tres puntos. Se aplicó ANOVA bidireccional seguido de la prueba de Tukey para comparar la resistencia a la flexión media de los grupos con y sin termociclado a un nivel de significancia de 0.05. Resultados: La resistencia a la flexión de la aleación de metal base, Zirconia y PEEK fue de 1387,70 ± 45,50 MPa; 895,13 ± 13,99 MPa y 192.10 ± 5,37 MPa, respectivamente. La diferencia fue significativa entre los grupos (p<0,001). El termociclado no tuvo un efecto significativo sobre la resistencia a la flexión de las muestras en ningún grupo (p=0,306).Conclusión: El polímero de alto rendimiento PEEK tiene una resistencia a la flexión más baja que la aleación de metal base y la cerámica de circonio, y su resistencia a la flexión no se vio afectada por el termociclado. PEEK parece ser capaz de resistir las fuerzas masticatorias en la cavidad oral, con la necesidad de más estudios in vitroy clínicos