Effect of TiB2 content on the characteristics of spark plasma sintered Ti–TiBw composites

Spark plasma sintering (SPS) was employed to fabricate monolithic titanium and in-situ formed TiB whisker (TiB_w) reinforced titanium matrix composites (TMCs) by adding different amounts of TiB₂ as boron source. The sintering process was completed at 1050 °C for 5 min under 50 MPa. The influences of TiB₂ content (0.6–9.6 wt. %) on microstructural evolution and mechanical properties of TMCs were investigated. Thermodynamics, XRD analysis and microstructural investigations confirmed the in-situ formation of TiB_w in the composite samples. However, some semi-reacted TiB₂ phases, surrounded by TiB coronas, were remained in the microstructure due to the unfinished chemical reaction between the components during a short-time sintering process. The results showed that all samples were appropriately densified by SPS process into the almost dense parts with relative density no less than 97.5%. While bending strength decreased and hardness increased with increasing TiB₂ content, the sample with 4.8 wt. % TiB₂ had the maximum tensile strength. Fractographical assessments showed that the addition of TiB₂ hindered the grain growth of titanium matrix. With increasing TiB₂ content, fracture mode changed from a multiple pattern to a predominantly transgranular and brittle state.     

Service based CAC with QoS guarantee in mobile wireless cellular networks

The increasing variety and complexity of traffic in today's mobile wireless networks means that there are more restrictions placed on a network in order to guarantee the individual requirements of the different traffic types and users. Call admission control (CAC) plays a vital role in achieving this. In this paper, we propose a CAC scheme for multiple service systems where the predicted call usage of each service is used to make the admission decision. Our scheme enables real‐time traffic to be transmitted using shared bandwidth without quality of service (QoS) requirements being exceeded. This ensures that the utilization of the available wireless bandwidth is maximized. Information about the channel usage of each service is used to estimate the capacity of the cell in terms of the number of users that can achieve a certain bit error rate (BER). Priorities assigned to each service are used to allocate the network capacity. An expression for the handoff dropping probability is derived, and the maximum acceptance rate for each service that results in the estimated dropping probability not exceeding its QoS requirements is calculated. Each call is then accepted with equal probability throughout the duration of a control period. Achieved QoS during the previous control period is used to update the new call acceptance rates thus ensuring the dropping probability remains below the specified threshold. Simulations conducted in a wideband CDMA environment with conversational, streaming, interactive and background sources show that the proposed CAC can successfully meet the hard restraint on the dropping probability and guarantee the required BER for multiple services. Copyright © 2005 John Wiley & Sons, Ltd.     

A graphical method for ranking Atanassov's intuitionistic fuzzy values using the uncertainty index and entropy

Many different types of ranking methods based on the score and accuracy functions of intuitionistic fuzzy values (IFVs) exist in the literature. The notion of knowledge bases, as in the case of rough set theory, is very handy to show that every ranking technique produces a unique classification of IFVs with a unique order among the classes. This means these rankings give rise to unique knowledge bases. Therefore, ranking of IFVs by two or more distinct techniques may produce different results. In this study, a graphical ranking method based on the uncertainty index and entropy is proposed. This approach is tested on several numerical examples existing in the literature and shown to be intuitive and convenient for applications in real-life scenarios.     

A Survey of Localization Systems in Internet of Things

Mobile Networks and Applications - With the rapid development in wireless technologies and the Internet, the Internet of Things (IoT) is envisioned to be an integral part of our daily lives....     

A Novel Approach to Optimize Power Consumption in Orchard WSN: Efficient Opportunistic Routing

Wireless Personal Communications - In orchard wireless sensor networks (WSN) application, the network link quality is unstable due to the shielding effect caused by the growth of branches and...     

Finding a Pareto Optimal Solution for a Multi-Objective Problem of Managing Radio Resources in LTE-A Systems: A QoS Aware Algorithm

Wireless Personal Communications - Due to ever increasing users demands, fulfilling the needs of growing users is challenging with constrained resources for Long Term Evolution- Advanced (LTE-A)....     

On improved monitoring of linear profiles under modified successive sampling

Control charts are often used for the monitoring of quality characteristics of interest. There may exist some other characteristics that are associated with the main quality characteristic. A model that quantifies the relationship between them is termed as a profile, for instance, the relation between charge and capacitance. The monitoring of the main variable that is linearly related with an associated explanatory variable is termed as simple linear profiles' monitoring. It is a common practice to use simple random sampling (SRS) for profile monitoring. This study intends to enhance profile monitoring by considering modified successive sampling (MSS) approach. The performance of the existing and the proposed schemes are evaluated using the well‐known metrics average run length. The comparative analysis revealed that the proposed structure outperforms the existing ones in terms of efficiency. A real application from electrical engineering is used to show the implementation of our proposal in practice.     

Synthesize and characterization of ceria based nano-composite materials for low temperature solid oxide fuel cell

The present study is focused on ceria based mixed (ionic and electronic conductor) composite Al_0.05Ni_0.1Ti_0.05Zn_0.80-SDC (ATZN-SDC) oxide material was prepared by solid state reaction, which can be used as anode materials for solid oxide fuel cell. The effect of Ti and Al oxides were analyzed on the NiZn-SDC composite with respect to its conductivity and catalytic activity in hydrogen atmosphere. The average crystallite size of the composite was found to be 40–100 nm by XRD and SEM. The DC conductivity was determined by 4-probe technique. The electrochemical impedance spectrum (EIS) was also examined in hydrogen atmosphere within a temperature range of 350–550 °C. The maximum power density 370 mW/cm² was achieved at 650 °C.     

Risk Assessment of Agricultural Water Conveyance and Delivery Systems by Fuzzy Fault Tree Analysis Method

Improving the efficiency of main Agricultural Water Conveyance and Delivery Systems (AWCDS) has a significant impact on improving water productivity in agriculture. Therefore, risk assessment of mentioned systems is necessary to increase reliability of operational performance. Accordingly, this study for the first time presents a unique framework to assess the adequacy, equity, and efficiency of agricultural water distribution and delivery risk assessment within AWCDS. In this way, the Fault Tree Analysis (FTA) technique is employed for risk assessment of “undesirability of supply and delivery”. The west Dez main irrigation canal in Khuzestan province of Iran was determined as the case study of the research. A set of questionnaires filled up by managers and experts of this irrigation district, the failure probabilities of the basic events are gathered in the form of linguistic terms. Due to the uncertainty in these terms, the system’s risk assessment to determine the failure probability of the top event was performed based on Fuzzy Fault Tree Analysis method (FFTA). The results of the study showed that the failure probability in the fuzzy approach is 0.55 which is roughly 0.15 more than crisp approach. Also, the rating of the basic events based on their contribution to the occurrence of the top event was carried out using importance measures. Five major events were identified with an emphasis on operational and socio-economic issues related to distribution and delivery of water. Comparing the results of risk assessment with the mathematical model reveals that the latter’s failure probability will be less than the system’s FTA due to non-consideration of some important factors.     

Economic incentives to use fertilizer on maize under differing agro-ecological conditions in Burkina Faso

Increasing agricultural productivity while protecting natural resources depends on proper understanding of farmers’ incentives to use intensification strategies, including fertilizer. Using a large-scale household dataset collected in rural Burkina Faso, we examined how the response of maize yield to fertilizer, and thus the economic incentives for its use, varied according to agro-ecological conditions. We employed a Control Function Approach with Correlated Random Effects in order to test and control for endogeneity of fertilizer use, measuring agro-ecological conditions at several scales. We investigated the profitability of fertilizer use with value-cost ratios. We found that productivity and marginal effects of fertilizer differ significantly according to agro-ecological conditions. Micro-variation appeared to be more critical than the definition of agro-ecological zone. Burkinabe soils are severely degraded and would benefit from greater application of fertilizer. However, at full market prices, fertilizer use was unprofitable. Though it was profitable with subsidized prices, transaction costs diminish the benefits of the subsidy. Profitability of fertilizer use with maize varied across agro-ecological conditions, even for field plots located in the same agro-ecological zone. Our results confirm that policy makers need to be cautious when generalizing across regions or drawing policy recommendations from a single agro-ecological zone because crop responses and economic incentives vary widely.