Considering the business system’s complexity with a network approach

Business management involves collecting information, goods, and funds as they move from supplier to manufacturer to wholesaler to retailer to consumer. Such business comprises interconnected parts that can be fundamentally complex and dynamic. A disturbance in one subnet of the system may thus have an opposed impact on another subnets, thus disturbing the business. Disruptions can have expensive and extensive results. This research aims to improve an increased Bayesian network method to consider business disruptions. The goal is to develop strategies that can diminish the opposed impacts of the disruptions and improve overall system reliability. Two influence agents are specified: the Bayesian and junction lack influence agents. An industrial model is used to demonstrate the proposed application, making the business more reliable. Moreover, two network learning methodologies are reviewed to update the probabilities in a model. The neural network seems to be a more favorable updating tool.     

Local behavior of column-tree connections with considering bolt-hole clearance and bolt pretension effects

In this paper, effects of bolt-hole clearance and bolt pretension level on seismic performance of column-tree moment resisting frames with reduced beam section have been investigated. In a typical constructional environment, manufacturing tolerances and field situations cause inappropriate positioning of bolts in their corresponding holes in bolted connections, so bolt-hole diameter increases by incorrect methods like acetylene gas cutting method. On the other hand, nonlinear local behavior of the connection elements and effects of dynamic friction during the process of applying the bolt pretension cause wrong evaluation of bolt pretension level. In order to investigate these problems, models of column-tree connections with various bolt-hole clearances and bolt pretension levels subjected to cyclic loading were developed and analyzed with 3D FEM and their hysteresis curves were obtained and evaluated. Results show that bolt-hole clearance can reduce the flexural capacity of column-tree connections especially along with reduction in the bolt pretension level while interstory drift angle increases during inelastic cycles.     

Correlation of waiting time with adverse events in patients admitted for nonelective permanent pacemaker implantation

OBJECTIVE: To determine the effect of a dedicated permanent pacemaker implantation procedure room on waiting time and waiting time-related morbidity. DESIGN: Retrospective chart review. SETTING: Two tertiary care teaching hospitals in southern Ontario; one with a dedicated procedure room (centre B) and one without (centre A). PATIENTS: Two hundred and fourteen consecutive patients who required permanent pacing urgently or emergently. METHODS: Charts were examined retrospectively at centre A (131 patients) and centre B (83 patients) to determine the waiting time for and the number of preoperative adverse events in nonelective permanent pacemaker implantation. RESULTS: Patients in centre A waited a mean of 4.5 +/- 3.0 days while patients in centre B waited a mean of 1.9 +/- 1.6 days (P = 0.0001). Centre A patients experienced a total of 57 adverse events that were likely or possibly related to the waiting period, while patients at centre B experienced eight such events (P < 0.0001). Thirty-three per cent of the centre A patients experienced at least one adverse event, while 8% of centre B patients experienced at least one adverse event (P < 0.00001). Of the centre A patients who waited for more than six days (26 patients), 58% had at least one adverse event, compared with 26% of those who waited less than six days (105 patients, P = 0.0009). CONCLUSIONS: Delays in implanting nonelective permanent pacemakers are strongly associated with an increase in adverse events. Measures to shorten the waiting time are likely to result in a reduction in morbidity in conjunction with a beneficial impact on health care resource utilization.     

Parameter optimization of microwave sintering porous Ti-23%Nb shape memory alloys for biomedical applications

Porous Ti-23%Nb (mole fraction) shape memory alloys (SMAs) were prepared successfully by microwave sintering with excellent outer finishing (without space holder). The effects of microwave-sintering on the microstructure, phase composition, phase-transformation temperature, mechanical properties and shape-memory effect were investigated. The results show that the density and size of porosity vary based on the sintering time and temperature, in which the smallest size and the most uniform pore shape are exhibited with Ti-23%Nb SMA after being sintered at 900 °C for 30 min. The microstructure of porous Ti-Nb SMA consists of predominant α″, α, and β phases in needle-like and plate-like morphologies, and their volume fractions vary based on the sintering time and temperature. The β phase represents the largest phase due to the higher content of β stabilizer element with little intensities of α and α″ phases. The highest ultimate strength and its strain are indicated for the sample sintered at 900 °C for 30 min, while the best superelasticity is for the sample sintered at 1200 °C for 30 min. The low-elastic modulus enables these alloys to avoid the problem of “stress shielding”. Therefore, microwave heating can be employed to sinter Ti-alloys for biomedical applications and improve the mechanical properties of these alloys.     

微波烧结生物医用多孔Ti-23%Nb形状记忆合金的参数优化（英文）

采用微波烧结法成功制备多孔Ti-23%Nb(摩尔分数)形状记忆合金(SMAs)(不含造孔剂)。研究微波烧结对合金显微组织、相组成、相变温度、力学性能和形状记忆效应的影响。结果表明,烧结时间和温度对合金密度和孔隙度大小的影响较大,在900℃下烧结30 min的Ti-23%Nb SMA具有最小的孔径和最均匀的孔形状。多孔Ti-Nb SMA的显微组织主要含有针状和片状的α"、α和β相,且体积分数随烧结时间和温度不同而变化。由于β相稳定元素的含量较高,因此β相含量最多,而α和α"相的含量较少。900℃烧结30 min的样品呈现最优的极限强度和应变,而1200℃烧结30 min的样品则具有最高的超弹性。这些合金的弹性模量较低,可以避免"应力屏蔽"效应。因此,微波加热可以应用于烧结生物医用Ti合金并提高其力学性能。     

A Novel Approach to Enhance the Mechanical Strength and Electrical and Thermal Conductivity of Cu-GNP Nanocomposites

Copper/graphene nanoplatelet (GNP) nanocomposites were produced by a wet mixing method followed by a classical powder metallurgy technique. A qualitative evaluation of the structure of graphene after mixing indicated that wet mixing is an appropriate dispersion method. Thereafter, the effects of two post-processing techniques such as repressing–annealing and hot isostatic pressing (HIP) on density, interfacial bonding, hardness, and thermal and electrical conductivity of the nanocomposites were analyzed. Density evaluations showed that the relative density of specimens increased after the post-processing steps so that after HIPing almost full densification was achieved. The Vickers hardness of specimens increased considerably after the post-processing techniques. The thermal conductivity of pure copper was very low in the case of the as-sintered samples containing 2 to 3 pct porosity and increased considerably to a maximum value in the case of HIPed samples which contained only 0.1 to 0.2 pct porosity. Electrical conductivity measurements showed that by increasing the graphene content electrical conductivity decreased.

     

Correction to: Efficient cooperative multicarrier underwater acoustic communication over the Persian Gulf channel

Wireless Networks - The original version of this article unfortunately contained a mistake in the author group, where Dr. Seyed Mehdi Hosseini Andargoli was not included as a co-author of the...     

A new approach to generating non-uniform support excitation at topographic sites

This study investigates different methods for generating non-uniform support acceleration at actual topographic sites. The factors affecting the non-uniform excitation of a topographic site include the time delay between the arrival times of incident waves at different soil depths, causing a phase difference, and the coherence function. The existing coherence models are based on data recorded on flat surfaces and are not suitable for surfaces with topographic features. Therefore, in the present study, models of a canyon site subjected to Ricker waves with different predominant frequencies, shear wave velocities, and shape ratios have been developed, and the results of boundary element analyses in the time domain (using the BEMSA code) have been obtained at different elevations on the canyon surface. Then, by conducting a statistical analysis employing the symbolic regression method on the results of numerous presumed cases, the relationships for calculating the time delay between the support responses and the coherence function of V-shaped canyons were obtained. To verify the accuracy of the proposed relationships, the results were compared with the records from the Pacoima Dam site during two different earthquakes and a good agreement was obtained between the results. Eventually, by implementing the proposed relationships in the random vibration method, the non-uniform acceleration of the site was simulated. The results indicate that the proposed relationships have an appropriate level of accuracy for calculating the time delay and the spectral coherence function of V-shaped canyons.     

A CMOS 3.2?Gb/s serial link transceiver, using a new PWAM scheme

In this article, a 3.2?Gb/s serial link transceiver, that can be implemented in 0.35???m CMOS technology is presented. In this transceiver a new multi-level pulse-width-amplitude modulation technique is used. The symbol rate is reduced, while the minimum pulse width (PW) is increased considerably, using the proposed modulation. The PW is larger than the conventional NRZ data format, with PW of Tb, so the ISI will be improved. The multiphase output of a three stage ring oscillator VCO in the PLL is used to modulate and to demodulate the signal. A new charge pump circuit is also introduced to decrease the mismatch between up and down paths. The peak to peak jitter of recovered clock is 21?ps at 800?MHz. The recovered data has the peak to peak jitter of 51?ps. The transmitter and receiver power consumption is 220 and 35?mW, respectively.