Social-aware dynamic router node placement in wireless mesh networks

The problem of dynamic router node placement (dynRNP) in wireless mesh networks (WMNs) is concerned with determining a dynamic geographical placement of mesh routers to serve mobile mesh clients at different times, so that both network connectivity (i.e., the greatest topology subgraph component size) and client coverage (i.e., the number of the served mesh clients) are maximized. Mesh clients are wireless devises associated with users, and in real world, the users with same interests or some social relationship have higher chance to gather and move together geographically, i.e., they form a community, and the WMN with multiple communities can be regarded as a social network. Therefore, this paper investigates the so-called social-aware WMN-dynRNP problem assuming that mesh routers should be aware of the social community structure of mesh clients to dynamically adjust their placement to improve network performance. To cope with this problem, this paper proposes a social-based particle swarm optimization approach, which additionally includes a social-supporting vector to direct low-loading mesh routers to support the heavy-loading mesh routers in the same topology subgraph component (community), so as to dynamically adopt to the social community behavior of mesh clients. As compared with the previous approach, our experimental results show that the proposed approach is capable of effectively reducing number of the unserved mesh clients and increasing network connectivity in dynamic social scenarios.     

Novel mold‐resistant building materials impregnated with thermally reduced nano‐silver

In this study, we evaluated the long‐term antifungal effectiveness of 3 types of interior building materials (gypsum board [GB], cement board [CB], and softwood plywood [S‐PW]) impregnated with thermally reduced silver nanoparticles supported by titanium dioxide (AgNPs/TiO₂) under 95% relative humidity for 4 weeks. AgNPs/TiO₂ was synthesized at 2 thermal reduction temperatures (TRTs, 120 and 200°C) with 2 different AgNP weight percentages (2 and 5 wt%). Four different silver‐loading levels (SLLs, 0.025, 0.05, and 0.5 μg/cm² and the critical concentration required to inhibit fungal growth on agar plates) and 3 fungal species (Aspergillus niger, Penicillium spinulosum, and Stachybotrys chartarum) were used in the experiments. Higher temperature reduced more ionic Ag⁺ to metallic Ag⁰ and increased the dispersion of Ag on TiO₂ surface. The 200°C thermally reduced AgNPs/TiO₂ demonstrated excellent antifungal efficiency: Mold growth was almost completely inhibited for 28 days at the low SLL of 0.5 μg/cm². Additionally, AgNPs/TiO₂ exhibited higher antifungal activity on GB and CB than on S‐PW. The stepwise regression results indicated that the TRT of AgNPs/TiO₂ (β = ?0.739 to ?0.51), the SLL (β = ?0.477 to ?0.269), and the Ag⁰ level in the AgNPs (β = ?0.379 to ?0.136) were the major factors influencing antifungal activity and TRT might be the most significant one.     

Value creation in production: Reconsideration from interdisciplinary approaches

This paper presents reconsideration of value creation in production from various aspects of value viewpoints in several disciplines such as production engineering, social sciences, and human sciences. The focal point of investigations is value co-creation by the provision of products and services in and for society. In the past, some methods of social sciences and others proved to be useful in making production more efficient. At present, such methods must help to realise value creation. In fact, production must become more effective in response to human needs in social, economic, and environmental dimensions. Along with the theoretical apparatus, this paper presents some case studies indicating the importance of value creation in production, followed by future perspectives of value co-creation in production.     

Ba1−xSrxCe0.8−yZryY0.2O3−δ protonic electrolytes synthesized by hetero-composition-exchange method for solid oxide fuel cells

This study reports the synthesis of proton-conducting Ba_0.8Sr_0.2Ce_0.6Zr_0.2Y_0.2O_3?δ oxides by using a combination of the sol–gel process and hetero-composition-exchange technique. The experimental results show that the sintered Ba_0.8Sr_0.2Ce_0.6Zr_0.2Y_0.2O_3?δ pellet synthesized by the hetero-composition-exchange method exhibits excellent sinterability, good relatively density, and high protonic conduction. Furthermore, the Pt/electrolyte/Pt single cell with such an electrolyte shows a significantly higher maximum power density as compared to those oxides prepared from conventional sol–gel powders. Based on the experimental results, we attempt to explain the improvement mechanism in terms of as-calcined particle characteristics and proton hopping distance. This work shows that the Ba_1?xSr_xCe_0.8?yZr_yY_0.2O_3?δ oxides synthesized by the sol–gel combined with hetero-composition-exchange method would be a promising electrolyte for H⁺-SOFC applications. More importantly, this new fabrication approach could be applied to other similar perovskite-type electrolyte systems.     

The effects of visualization format and spatial ability on learning star motions

The purpose of this study was to investigate not only the effectiveness of dynamic versus static visualizations on learning star motions but also the influence of students' spatial abilities with these two types of visualizations on their learning. We assigned 155 fifth-grade students to either a dynamic or a static condition. We used a science achievement test to measure student learning outcomes by assessing knowledge acquisition. We classified students as having either a low or high spatial ability based on their test scores for primary mental abilities, specifically spatial relations. The results showed that dynamic visualizations were more effective than static visualizations for learning complex concepts involving star motions. Furthermore, learners' spatial abilities had a positive effect on their learning outcomes but did not moderate the effectiveness of dynamic versus static visualizations for learning in this domain. Our findings suggest that when designing instructional materials, the dynamic properties of visualizations should be aligned with the dynamic nature of the subject matter. We conclude that students' spatial abilities are beneficial to learning, especially when they are studying a complex domain that demands spatial changes and moving processes; therefore, our findings support the importance of assessing spatial ability in learning with visualizations.     

The operating performance and products distribution of the catalytic oxidation of methyl-isobutyl-ketone over a Pt/gamma-Al2O3 catalyst

Catalytic oxidation is one of the cost-effective technologies to solve the troublesome volatile organic compounds. This study treated methyl-isobutyl-ketone (MIBK) by a commercial catalyst, Pt/gamma-Al(2)O(3), in a fixed-bed reactor. The effects of operating factors, such as operating temperature, MIBK concentration, space velocity, and O(2) concentration, on the performance of the catalyst were investigated. The products and reactants distributions from the oxidation of MIBK over Pt/gamma-Al(2)O(3) were observed. The results show that the products containing carbon atoms are CO, CO(2), and C(3)H(6)O. Two catalyst life-tests were also carried out to characterize the deactivation effect of MIBK. The result shows that the deactivation effect may be due to the coke on the catalyst surface at 423 K. From the statistical analysis, the operating temperature is the most effective factor on the conversion of MIBK. The catalysts were also characterized by surface area analysis and elemental analysis before and after the test. The results show that the catalytic deactivation may be due to carbon coating. At low temperature (423 K), the phenomenon of carbon coating was more obvious than that at high temperature (573 K). The product distributions from the oxidation of MIBK over Pt/gamma-Al(2)O(3) were analyzed by GC. The results indicate that the C(3)H(6)O is formed from the beginning, presenting a peak at 423 K, 6.54 ppm. The CO concentration also peaked at the same temperature, 6.84 ppm.     

Polyaniline nanofiber/gold nanoparticle nonvolatile memory

A nonvolatile plastic digital memory device based on nanofibers of the conjugated polymer polyaniline decorated with gold nanoparticles is reported. The device has a simple structure consisting of the plastic composite film sandwiched between two electrodes. An external bias is used to program the ON and OFF states of the device that are separated by a 3-orders-of-magnitude difference in conductivity. ON-OFF switching times of less than 25 ns are observed by electrical pulse measurements. The devices possess prolonged retention times of several days after they have been programmed. Write-read-erase cycles are also demonstrated. The switching mechanism is attributed to an electric-field-induced charge transfer from the polyaniline nanofibers to the gold nanoparticles. The active polymer layer is created by growing nanometer size gold particles within 30-nm-diameter polyaniline nanofibers using a redox reaction with chloroauric acid. This device combines two exciting research areas--nanoparticles and conducting polymers--to form a novel materials system with unique functionality.