Convergence of multivalued mappings via approximable measurable selectors

We investigate the convergence of measurable selectors for the limit of measurable multivalued maps. The relationship between the convergence of measurable selectors and lower and upper limits of measurable multivalued mappings with closed images is also derived.     

Resputtering-induced chemical inhomogeneity during the growth of highT c superconductor thin film

HighT _c films belonging to Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems have been fabricated by reactive sputtering of single targets in a planar magnetron and Ar + O₂ sputtering atmosphere. Although it was possible to deposit films of correct composition, resputtering related composition variation was a problem. The key to obtaining correct chemistry was a proper control of the deposition parameters. The pressure and oxygen content of the sputtering gas were found to be the most critical parameters. Results of the variation of these parameters on the cation chemistry are presented in this paper. Results from Monte-Carlo simulation of the sputtering process are also presented showing that low pressure and oxygen content of the sputtering gas result in a higher yield of energetic reflected neutrals which can cause compositional variation in the film mainly due to preferential sputtering of the growing film. The effect was particularly noticeable directly underneath the target. The energetic particle bombardment can be controlled by using moderately high pressures and low oxygen concentration in the gas.     

Myth and reality of the hybrid desalination process

The paper discusses some misconceptions that have contributed to the continued use of thermal desalination processes and promotion of the hybrid desalination process for new plants being built or considered at Middle East locations. The misconceptions are examined both on the basis of fundamental thermodynamic principles and in terms of practical engineering parameters. The analysis shows that there is no economic or performance advantage in the installation of greenfield hybrid power/thermal desalination/ seawater reverse osmosis (SWRO) plants in preference to power/SWRO plants, because the latter would produce water more cheaply under all conditions and at all fuel costs, and would provide more operational flexibility than the former. The paper identifies situations where the hybrid desalination process can be fully justified: in existing power/desalination plants, where aging boilers and multistage flash (MSF) units need to be repaired or replaced, through retrofitting and repowering. In such situations, abandonment of the MSF process would result in a reduction in the power output of the plant. The paper refers to previous work which showed that the repowering of a typical existing power/desalination station with refurbishment/replacement of the MSF units, together with the addition of SWRO units, would result in a several-fold increase in the water and power output and a dramatic improvement in the fuel efficiency, without any additions to the existing seawater intake system. The paper emphasizes the importance of test stations/demonstration plants at existing power/desalination stations in the Middle East in order to obtain data and make improvements in the technology of higher temperature SWRO, with the feed obtained from the cooling water returning from the power plant condenser and the thermal desalination plant. The paper shows that the potential benefits would easily justify the investment in research and development required to validate this concept.     

Degradation of chlorinated polyethylene—III: Effect of additives on dehydrochlorination and oxygen absorption

Degradation of chlorinated polymers takes place via two simultaneous reactions; namely, dehydrochlorination and oxygen absorption. The dehydrochlorination and oxygen absorption of five grades of chlorinated polyenthylenes were studied at temperatures varying between 120 and 180°C. The chlorinated polyethylene grades varied in both molecular weight and chlorine content, the latter being in the range of 24.0 to 45.2 percent chlorine. Dehydrochlorination measurements on the pure polymers in both nitrogen and oxygen atmospheres showed that the rate of dehydrochlorination increases with an increase in the degree of chlorination of the polymer. The oxygen absorption rate, however, showed a decrease with higher chlorine content of the polymer. Dehydrochlorination and oxygen absorption studies were also carried out on chlorinated polyethylene containing dehydrochlorination stabilizers, antioxidants, antimony oxide, and other metal salts and metal oxides. Retardation of both oxygen absorption and dehydrochlorination was observed in the presence of antioxidants. More significant, however, was the observed action of some dehydrochlorination stabilizers as efficient antioxidants in the polymer.     

Aggregation Operators of Interval‐Valued 2‐Tuple Linguistic Information

The group decision‐making problem with linguistic information evaluation values of decision makers are used based on 2‐tuple interval‐valued. Operational laws on interval value 2‐tuple are introduced. On the basis of these laws, new aggregation operators are introduced by using the Choquet integral. A multiple attribute decision‐making method based on these aggregation operators is proposed. An example is given to illustrate the efficiency, practicality, and feasibility of our method.     

Electrospinning of polycaprolactone nanofibers using H2O as benign additive in polycaprolactone/glacial acetic acid solution

Considerable efforts have been devoted to the production of polycaprolactone (PCL) nanofibrous structures by electrospinning. However, some toxic solvents have often been used to achieve bead‐free nanofibers. At present, a benign solvent such as glacial acetic acid (GAC) only leads to beaded or microscale fibers. Therefore a study is done to extend the electrospinnability of the PCL/GAC system by the addition of H₂O. The solution properties of conductivity, viscosity, and surface tension were altered by the addition of H₂O, especially increasing the conductivity and viscosity. These properties essential to electrospinning could remain stable for 6 h when the H₂O content was less than or equal to 9 vol %. Then ultrafine PCL fibers with diameters from 188 to 200 nm, 10 times smaller than when dissolved in pure GAC, were electrospun from solutions of PCL with concentrations in the range of 17 to 20 wt % with H₂O content at 9 vol %. Finally, the crystallinity and crystallite size of the resulting fibers were smaller than that of raw PCL pellets. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45578.     

Oriented polycrystalline mesoporous CeO2 with enhanced pore integrity

Mesoporous CeO₂ particles are synthesized using a sol–gel method involving Pluronic P123 or F127 tri-block copolymer and cerium acetate hydrate. Transmission electron microscopy reveals well defined meso-channels of about 10 nm in diameter and a wall framework consisting of highly oriented polycrystalline CeO₂. The [0 0 1] axis of the crystals is found to be aligned parallel to the meso-channels, and lattice coherency of [1 0 0] or [0 1 0] also exists in perpendicular plane to the channel. A cooperative self-assembly of the tri-block copolymer and Ce⁴⁺ species is believed to occur, along with the precipitation of nano-crystalline CeO₂ in the sol–gel process. It is proposed that the preferential orientation may result from a favored linkage of the low-order Miller indices {0 0 1} planes of CeO₂ to the PEO segment in the PEO–PPO–PEO tri-block copolymer micelles. The unique structural characteristics of meso-CeO₂ appear to contribute to maintaining the pore integrity during the synthesis as well as in a post-fabrication in situ TEM heating test.     

Iodine treatment of nylon: Effect on metal plating of the polymer

The iodine treatment of nylon surfaces consist essentially of dipping the nylon in an iodine—potassium iodide solution and quickly rinsing the absorbed iodine out of nylon surfaces using glycol—water—thiosulfate as a wash solution. The treatment was found to profoundly affect the adhesion between the nylon and an electrolessly deposited metal on its surface. The adhesion changes from no adhesion for an untreated nylon surface to a maximum of 28 lb/in. for a treated sample. The adhesion is dependent mainly on the nature of the nylon surface (crystallinity, molecular weight, etc.), the duration of the iodine treatment, and the nature and conditions of the wash solution. Electron microscope pictures of the nylon surface after the iodine treatment show a shallow etching pattern, and therefore mechanical keying between the metal and the polymer is not a probable factor of importance. Under certain experimental conditions, the iodine treatment changes the crystallinity from the α-form predominant in the nylon before treating the sample to the γ-form. It also decreases the overall crystallinity of the surface, softens the polymer, and improves its water wettability. All the above changes enhance a more intimate interaction between the deposited metal and the polymer.     

Performance Model of a WIMAX 2.0 All-IP 4G System

4G is promising a wireless broadband with data rates up to 1Gbps. The two candidate technologies for 4G are the Advanced Long Term Evolution (Advanced LTE) which is based on the 3GPP standards and the WiMAX 2.0 based on the IEEE 802.16 family of standards. The common feature of both technologies is that they will provide All-IP connectivity with flexible bit rates and quality of service guarantees for multiple classes of services including voice, mainly using voice over IP, data and video services. Most of the performance studies of 4G technologies use highly complex and sophisticated simulations due to the multiple complexity factors in investigating 4G technologies such as All-IP flexible bit rates, adaptive coding and modulation as well as the multi-services provided. These factors usually make any modelling attempt very difficult. This paper presents a numerical/analytical model for a 4G WiMAX cell based on a multi-dimensional Continuous-Time Markov Chain (CTMC) model. Performance measures were derived for the key performance indicators such as throughput and average bit rate per cell and per service class. By assuming minimum acceptable bit rates for certain quality of service guarantees, we derived measures for blocking probabilities. The model has been formulated and solved using MOSEL-2 (Modelling Specification and Evaluation Language) which captures the key features of a 4G system that affect services at session/call level. The resuls obtained from the model using sample parameters show that, the model can provide very useful insight to system behavior and can give good first indication to the performance of such a complex system.