On the installation of an in situ large-scale vertical SEALing (VSEAL) experiment on bentonite pellet-powder mixture

Recently,the Institute for Radiological protection and Nuclear Safety(IRSN)has launched VSEAL(Vertical SEALing)project to investigate the impact of gas migration on the long-term performance of bentonite based vertical sealing systems(VSS).The first VSEAL in situ test was emplaced in IRSN’s Underground Research Laboratory(URL)in Tournemire(France)in 2019 and was equipped with 76 wired and wireless sensors.The test is still in progress,but the collected set of data provides already valuable information of the hydro-mechanical behavior of VSS during hydration.The swelling core consists of a mixture of highdensity pellets and powder of MX80 bentonite in a ratio of 80/20(in dry mass).An innovative method was adopted to drill a 1-m diameter and w10-m deep shaft in order to minimize the rock perturbation at the sidewalls.Because a specific protocol was adopted to install the bentonite mixture together with a careful characterization of the core during construction,VSEAL 1 constitutes the unique in situ sealing test with a well-known initial structural distribution of the pellets and the powder.Some heterogeneities occurred within the experiment during the installation process:a damaged zone developed around the shaft walls due to the interruption of the installation operations caused by COVID19 lockdown in France;a technological gap with a variable thickness between the last pellets layer and the top confining lid and a heterogeneous distribution of the bentonite powder at some layers inducing large inter pellets voids close to the bentonite-rock interface.Artificially injected water volume,relative humidity,water content and swelling pressure in both radial and axial directions were monitored.Comparison of the results showed that the presence of installation-induced heterogeneities led to the generation of preferential flow paths that influenced the swelling pressure evolution at radial and axial directions.

Promotion of Improved Sorghum Technologies through Large-Scale Demonstration in Gololcha Woreda, Arsi Zone of Oromia Regional State, Ethiopia

The study was carried out to improve farmers’ awareness, enhance the adoption of full package sorghum production technologies. The large-scale demonstration was implemented at Gololcha woreda of Arsi zone for one year (2019/2020) using Melkam variety. The demonstration was implemented in three kebeles and a total of 100 hectares of land was covered by participating 117 household heads (farmers) out of which 12 of them were women-headed. In the demonstration farmers contributed a land size of 0.25 hectares (the minimum) and 2 hectares of land (maximum). Totally, from the demonstration 4030 quintals of sorghum were harvested with 42.3 quintals per hectare average productivity. The yield obtained by farmers practices was 18.23 q·ha-1 which is lower as compared to the average yield obtained by large scale demonstration. The technology gap (TG) was 15.70 q·ha-1 which indicated that technologies have not been adopted. Extension gap was 24.07 q·ha-1 and this result indicated that the extension approach should be more strengthened. It has been ascertained that “Melkam” variety is the best fitted variety and promotion of improved sorghum technologies via large scale demonstration has shown a considerable yield increment as compared to farmers practices. According to the farmers’ trait preference, Melkam variety was preferred by farmers because of its high yielding, consumption quality, early maturity, palatability, and drought-tolerant traits respectively. For sustainable production of improved sorghum technologies, the seed system should be taken into consideration to deliver the seed supply for the entire sorghum producers.

Broadband millimeter-wave metasurface antenna array withprinted ridge gap waveguide for high front-to-back ratio

A novel broadband metasurface (MTS) antenna array with high front-to-back ratio (FBR) is proposed for 28 GHz millimeter-wave applications. With slot pairs loaded on patch cells, an aperturecoupled slotted-mushroom MTS antenna is designed to obtain broadband radiation characteristicswith a compact size. To suppress the backward radiation of this antenna, the printed ridge gapwaveguide (PRGW) technology with a perfect magnetic conductor (PMC) shielding made ofmushroom unit-cells underneath the microstrip feeding line is applied. On this basis, a 4×4 MTSantenna array with the PRGW feed network is developed. Simulated results show that the FBR canbe highly improved by over 16 dB within the entire bandwidth. To validate the design, a prototypeof the proposed antenna is fabricated. Measured results show that an FBR greater than 28 dB canbe obtained over a 24% impedance bandwidth (from 24.9 GHz to 31.7 GHz) with the reflectioncoefficient less than 10 dB. The measured antenna gain ranges from 17 dBi to 19.2 dBi and thecorresponding measured aperture efficiencies are 35% and 45.6%. The measured results alsosuggest that the proposed MTS antenna possesses -35 dB cross-polarization level and stable radiation patterns. In addition, the proposed antenna remains a very low profile of 1.7 mm (0.17λ_(0) at28 GHz). All the achieved features indicate that the proposed MTS antenna is an importantcandidate for B5G and 6G wireless communication.

Study on the Optimal Localization Rate for Shipbuilding Industry in China

In China,the target setting on loading rate of domestic equipment for shipbuilding industry has not been studied from a perspective of an optimization problem.Based on the constant elasticity of substitution production function,a localization rate model for shipbuilding industry is established to investigate the government's trade-off between the interest of shipbuilding industry and that of ship supporting industry and to set the optimal localization rate.The results show that the market capacity has a significant effect on localization rate.In particular,when the market capacity is too small,the optimal localization rate is zero.When the market capacity is too large,the optimal localization rate is one.When the market capacity is in a certain range,a regular localization rate target exists.Moreover,the optimal localization rate could be affected by the technology gap and prices of domestic and foreign marine equipments.When the market capacity is large and the technology gap between domestic and foreign marine equipments is small,or the price of domestic equipment is too low,a higher localization rate target should be set.Finally,the substitutability of domestic and foreign equipments affects the optimal set of localization rate.If the substitutability of domestic and foreign equipments is too low,the improvement of localization rate caused by technological progress or price reduction of domestic equipment will be limited.This study provides several significant policy suggestions on dynamic adjustment of localization rate,classified implementation,and core technology mastering.