An integration of mixed VND and VNS: the case of the multivehicle covering tour problem

The multivehicle covering tour problem (m‐CTP) is a transportation problem with different kinds of locations, where a set of locations must be visited while another set must be close enough to planned routes. Given two sets of vertices V and W, where V represents the set of vertices that may be visited and W is a set of vertices that must be covered by up to m vehicles, the m‐CTP problem is to minimize vehicle routes on a subset of V including T, which represents the subset of vertices that must be visited through the use of potential locations in V. The variant of m‐CTP without a route‐length constraint is treated in this paper. To tackle this problem, we propose a variable neighborhood search heuristic based on variable neighborhood descent method. Experiments were conducted using the datasets based on traveling salesman problem library instances.     

Dual‐band ridge waveguide filters for high‐selectivity wireless base station applications

Dual‐band filters simplify the system architecture considerably by replacing doubly multiplexed filters. This is especially important in base stations for wireless communications, where high‐selective filtering functions are required, with very stringent requirements in size and insertion losses. For this goal, compact dual‐band filters realized in air‐filled metallic ridge waveguides are proposed. The dual‐band approach shown in this article allows fulfilling the stringent insertion loss specifications of very selective filtering functions. The ridge waveguide resonators are placed in a canonical folded top‐bottom structure layout. Coupling sections that provide cross‐couplings are realized by irises opened in the intermediate wall. Given the high‐order of the dual‐band filter required for actual wireless applications, an efficient modeling by the mode‐matching method is used. A complete challenging filter prototype with 16 poles and 10 transmission zeros with specifications of typical wireless transceivers is built and tested for verification. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:703–712, 2016.     

E and H‐plane wide‐band ridge waveguide couplers

A systematic synthesis procedure for ridge waveguide branch line couplers in both E‐plane and H‐plane configurations is presented. Ridge waveguides are chosen to benefit from their wide mono‐mode band and compact size compared to rectangular waveguides. Equivalent circuit parameters are used to synthesize the coupler sections. Rigorous mode matching method is used for full‐wave analysis and optimization of the couplers. Ridge couplers both in empty waveguide and Low Temperature Co‐fired Ceramic “LTCC” technology are designed using the proposed method and the design is verified with another numerical method. A prototype is built and its response is measured to verify the approach. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

DOC removal by multi-stage ozonation-biological treatment

Multi-stage ozonation-biological treatment process for dissolved organic carbon (DOC) removal was evaluated to apply for drinking water treatment. Waters with different types of DOC were used, i.e. a reservoir water for drinking water supply, a secondary effluent from a municipal wastewater treatment plant and a solution of humic substances extracted from leaf mold. The multi-stage ozonation-biological treatment process was compared with conventional single-stage ozonation-biological treatment process. Amount of DOC removed in biological treatment was defined as amount of biodegradable dissolved organic carbon (BDOC) in influent of biological treatment. DOC removal in the multi-stage ozonation-biological treatment was higher than that in the conventional single-stage ozonation-biological treatment with the same total ozonation time for the reservoir water and humic substances solution. Moreover, three- or four-stage ozonation for 5 min followed by biological treatment (total ozonation time 15 or 20 min) showed higher removal of DOC than the single-stage ozonation (60 min) and biological treatment. The higher DOC removal in the multi-stage treatment was due to the production of BDOC by ozonation. The long-term ozonation was not effective to produce BDOC because most of ozone was utilized to oxidize BDOC produced in the early stage of ozonation. In the multi-stage treatment, ozonation was effective to decompose refractory DOC and to produce BDOC because BDOC was removed by biological treatment. However, multi-stage ozonation-biological treatment was not effective for the secondary effluent. The reason seems to be high concentration of ozone scavengers in that water and low reactivity of DOC for ozone.     

Enhancement of fiber–matrix adhesion by laser ablation-induced surface microcorrugation

Micrometer-sized surface corrugations produced on Kevlar fiber surfaces by laser ablation were found to dramatically enhance the mechanical adhesion between the fibers and the epoxy matrix in a fiber-reinforced composite. Symmetric and asymmetric corrugation structures were produced by irradiating the fibers with high-fluence UV laser pulses at various incidence angles. The interfacial shear strength (IFSS) between the fibers and the matrix was measured using the microbond fiber-pullout method. Upon laser ablation treatment, the IFSS increased by 120% with symmetric corrugation profiles obtained with laser irradiation normal to the fiber axis, and 5-fold with asymmetric corrugation profiles obtained with the laser incidence angle at 45° to the fiber axis. A similar enhancement was observed in pullout tests under wet conditions. A simple model based on an elementary analysis of the expected strain field in the presence of interface corrugation is found to provide a quantitative explanation of the observed strength enhancement factors.

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Is agriculture connected with stunting in Indonesian children living in a rice surplus area? A case study in Demak regency,central Java

Central Java province plays the main role in the production of food for national stocks in Indonesia, in which Demak is one of the 35 Regencies. Demak Regency had the sixth highest rice productivity in 2013, but at the same time, the seventh highest percentage of child malnutrition. This paradox between high rice productivity and low nutritional status of children triggered an interest in analyzing the correlations between agricultural production of households in the Demak Regency and the prevalence of stunting of children under-five. In December 2014 to February 2015, a cross-sectional survey was carried out in three sub-districts in Demak (Karanganyar, Dempet and Gajah) having the highest rice production and at the same time poor nutritional status of under-five children. The oldest under-five children from farmer family backgrounds were selected. Data on general characteristics, anthropometry of the children, as well as household socio-economics, including agricultural characteristics were obtained. Of the 335 children, 31.9% of them were stunted. A higher proportion of households that grew rice solely or mainly for own consumption (62.4%) and had significantly smaller sized rice-fields (p = 0.041) had stunted rather than non-stunted children. In total, rice production, farm income and agriculture diversity of families with non-stunted children were not significantly different from those of stunted children. However, yearly expenditure for improving family health and environmental conditions were significantly higher among non-stunted than stunted children (p = 0.044). Family decisions about what to spend money on also seemed to influence the nutritional status of the children, rather than nutritional diversity or revenue from agriculture itself. Therefore, improvement of agricultural production and diversity should be accompanied by education on household expenditure.