Improving the anti-corrosion properties via surface modification for silicon dioxide by conductive polymer

The modification of silicon dioxide surface via polyaniline (PANI) prepared by in-situ polymerization method. PANI and PANI-SiO 2 were characterized using Fourier transform infrared; X-ray diffraction and digital multimeter was used to measure conductivities for samples. Morphology of the synthesized PANI and PANI-SiO2, were examined using scanning electron microscopy. Samples were then used as pigments through blended with acrylic paint and applied on the surface of carbon steel panels. Corrosion was evaluated for coating of carbon steel panels through; full immersion test, salt spray test and adhesion test up to standards; ASTMG 31, ASTM B117 and ASTM D3359 respectively. Corrosion rate and coating adhesion were calculated after finished exposed periods in acidic Medias. Digital camera also used for monitored corrosion visually on the surface of carbon steel specimens. The results revealed that acrylic paint pigmented by SiO2 modified by polyaniline, more efficiently in corrosion protection for carbon steel than each of PANI and SiO2

The service required quality ensure model of LTE technology downlink

У статті запропонована математична модель розподілу ресурсних блоків у низхідному каналі зв’яз- ку технології LTE. Запропонована модель спрямована на забезпечення гарантованої якості обслуговування користувачів безпроводової мережі шляхом виділення для користувацьких станцій необхідних швидкостей передачі. Проведено порівняльний аналіз отриманих рішень при використанні різних цільових функційВ статье представлена математическая модель распределения ресурсных блоков в нисходящем кана- ле связи технологии LTE. Предложенная модель направлена на обеспечение гарантированного каче- ства обслуживания пользователей беспроводной сети путем выделения пользовательским станциям требуемых скоростей передачи. Проведен сравни- тельный анализ получаемых решений при использова- нии различных целевых функци

The Characterisation of the Strength Development of A Cement-Stabilised Soft Soil Treated with Two Different Types of Fly Ashes

There are several problems associated with soft soils such as the low strength, high compressibility and the sensitivity with the changes in the water content. In order to mitigate such undesirable properties, soft soils are often improved and stabilised either mechanically chemically. However, chemical stabilisation is the most effective technique to improve the geotechnical properties of the soft soil. This study aims to improve the properties of a soft soil regarding the consistency and compressive strength by using a small amount of cement (5% OPC by the dry weight of the treated soil). Then two different types of fly ash were examined for pozzolanic activation of the cement treated soil. These fly ashes were pulverised fuel ash (PFA) and palm oil fuel ash (POFA). Initially, trial specimens containing 5% OPC with 5% of PFA or POFA were prepared for unconfined compressive strength testing (UCS) conducted at 7 days of curing. These trial specimens were manufactured to indicate with which type of fly ash the future research should be based on. The results of UCS test revealed that PFA indicated higher strength than that for POFA after 7 days of curing. Thus PFA was considered in this study as a pozzolanic activator for further experimental works. Additionally, the cement-stabilised soil (CSS) mixture was mixed with PFA with different proportions where OPC was kept as 5% and PFA was varied from 5–15% by the dry weight of the stabilised soil. The improvement levels in the stabilised soil were evaluated dependent on the results of UCS test conducted on specimens of CSS treated with different percentages of PFA and subjected to two different periods of curing (7 and 28 days). The effect of PFA on the compaction parameters (maximum dry density (MDD), optimum moisture content (OMC)) and Atterberg limits (liquid limit (LL), plastic limit (PL), along with the plasticity index (PI)) of the CSS soil was also explored in this study. The plasticity characteristic of the treated soil was found to decrease with continuous increments of PFA. The PI decreased from 20.3 for the untreated soil to 13.75 for the cement stabilised soil treated with 10% PFA. The optimised mixture in this research was found to be (soil + 5% OPC + 10% PFA) which increased the UCS of the soil from 134kPa for the virgin soil (VS) and 732kPa for the soil treated with only 5% OPC cured for 28 days to 946kPa at an equivalent 28 days of curing

Call Admission Control for Non-Standalone 5G Ultra-Dense Networks

Abstract—In this letter, we propose new handoff schemes to reduce the interruption time that occurs during re-connection of an arriving mobile user moving from macrocell to small cell or from small cell to macrocell domains. A new call admission control (CAC) function is developed to adjust thresholds during handoff request signaling. To perform the handoff operation, Markov chain technique is used to analyze the call blocking probability characteristic and subsequently to decide handoff approval for various subscriber requests. Numerical results show that the proposed admission control mechanism is able to minimize call blocking probability, without sacrificing resource utilization, and to reduce the number of service interruptions occurring during user re-connections

Spectrum handoff management in cognitive hetnet systems overlaid with femtocells

Cognitive radio networks can facilitate seamless mobility to users considering their effective use of the dynamic spectrum access. This is performed by proactive/reactive adaptation of transmission operations in response to the wireless environment changes. One of these operations includes handoff between various wireless domains. The handoff here is not just a registration with a new base station, but it is also a negotiation to get access to the available channels locally in coexistence with the primary users. This dynamic adaptation between channels, known as spectrum handoff (SH), significantly impacts the time of handoff reconnection, which raises many questions about the functioning of the cognitive radio solution in the next generation of network systems. Therefore, it is necessary to develop a new method for roaming mobile users, particularly networks that employ small cells such as femtocells in order to reduce the unnecessary channel adaptations. This paper proposes a new entity, namely, channel assigning agent for managing SH, operator database, and channel access authentication. The goal of this mechanism is to retain the same channel used by a mobile user whenever possible to improve network performance by reducing the unnecessary SHs. The modeling and efficiency of the proposed scheme are validated through simulation results. The proposed solution improves the accessibility of resources and stability ofmobile radio connections that benefits mobile users as well as operators

The Development of a Low Carbon Cementitious Material Produced from Cement, Ground Granulated Blast Furnace Slag and High Calcium Fly Ash

This research represents experimental work for investigation of the influence of utilising Ground Granulated Blast Furnace Slag (GGBS) and High Calcium Fly Ash (HCFA) as a partial replacement for Ordinary Portland Cement (OPC) and produce a low carbon cementitious material with comparable compressive strength to OPC. Firstly, GGBS was used as a partial replacement to OPC to produce a binary blended cementitious material (BBCM); the replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of OPC. The optimum BBCM was mixed with HCFA to produce a ternary blended cementitious material (TBCM). The replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of BBCM. The compressive strength at ages of 7 and 28 days was utilised for assessing the performance of the test specimens in comparison to the reference mixture using 100% OPC as a binder. The results showed that the optimum BBCM was the mix produced from 25% GGBS and 75% OPC with compressive strength of 32.2 MPa at the age of 28 days. In addition, the results of the TBCM have shown that the addition of 10, 15, 20 and 25% of HCFA to the optimum BBCM improved the compressive strength by 22.7, 11.3, 5.2 and 2.1% respectively at 28 days. However, the replacement of optimum BBCM with more than 25% HCFA have showed a gradual drop in the compressive strength in comparison to the control mix. TBCM with 25% HCFA was considered to be the optimum as it showed better compressive strength than the control mix and at the same time reduced the amount of cement to 56%. Reducing the cement content to 56% will contribute to decrease the cost of construction materials, provide better compressive strength and also reduce the CO2 emissions into the atmosphere

Shear performance of beam-column joints subjected to high loading rates

High loading rates may produce in structural frames due to some actions, such as explosions or debris impact. The response of structural members to such abnormal loadings should be investigated to provide comprehensive knowledge of their capability to resist impulsive forces. The beam-column joint is considered one of the most important structural components that significantly control the robustness and integrity of a structural frame. Hence, in the current study, eight full-scale specimens of two types of beam-column joints were tested under dynamic impact load to study their response to high rate load. These two types of joints were fin-plate and single angle-cleat joints. The tests were carried out using a drop hammer to apply an impact load on the specimens from different heights with different preloading conditions. The single angle-cleat joints exhibited a better response to dynamic loads with different impact height and preloading conditions than fin-plate joints in terms of resistance and ductility. Bolt shear failure was the dominant failure mode of the two types of the joints selected

Effect of humic acids and the amount of mineral fertilizer on some characteristics of saline soil, growth and yield of broccoli plant under salt stress conditions

Saabunud / Received 09.04.2022 ; Aktsepteeritud / Accepted 19.06.2022 ; Avaldatud veebis / Published online 19.06.2022 ; Vastutav autor / Corresponding author: Duraid K. A. Al-Taey ; [email protected] (A pots experiment was undertaken to determine the combined effect of humic acids and mineral fertilizer on some characteristics of saline soil, growth, and yield components of broccoli. The experiment was conducted in a randomized complete block design with three replications. The first factor consists of two levels of humic acids, namely without humic acid (H0 = 0.00 g L–1 ) and humic acid application (H1 = 0.35 g L–1 ), while the second factor included nine fertilizer (92 kg N ha –1 , 200 kg P2O5 ha–1 , 150 kg K2O ha–1 ) application rates that were (100, 100, 100%), (120, 120, 120%), (120, 120, 100%), (80, 120, 120%), (100, 100, 120%), (80.100, 100%), (120, 80, 80%), (100, 80, 80%), (80, 80, 80%) which added as a percentage of original fertilizer recommendation taking the symbols of R1 to R9 respectively. The treatment R1 was designated as a control treatment. The results indicated that humic acid application (H1) and increasing the amount of applied mineral fertilizer (R2) reduced the hydraulic conductivity of the soil for different soil depths. Humic acid addition (H1) increased concentrations of calcium and magnesium while reducing sodium concentration compared to control (H0). Contrary to humic acid, increasing the supplied mineral fertilizer led to a reduction in concentrations of calcium and magnesium while increasing sodium concentration in the soil. The sodium adsorption in soil particles in the ground was decreased due to humic acid application while improving the mineral fertilizer. Humic acid (H1) combined with increasing the amount of chemical fertilizer (R2) gave the desirable results in decreasing the sulphate, chloride and bicarbonate in the soil profile. The addition of humic acid (H1) and increasing mineral fertilizer application (R2) led to a significant increase in plant height, leaf area and head weight of broccoli per plant. Similarly, the interaction between humic acids and chemical fertilizers (H1R2) led to a significant increase in plant height, leaf area and head weight of broccoli per plant

Effect of deposition time on the characteristics of nanocrystalline cds thin films and photodetection properties

Nanocrystalline CdS thin films were grown on silicon substrates using microwave-assisted chemical bath deposition. Aqueous solutions of cadmium chloride (CdCl2) and thiourea [SC(NH2)2], which served as cadmium Cd2+ and sulfur S2– ions sources, respectively were used to synthesize the nanocrystalline CdS thin films. Morphological, structural, and optical analyses revealed that the deposition time have significantly influenced the properties of the prepared thin films. CdS thin film prepared at a deposition time of 20 min showed the optimum characteristics. The photoluminescence measurements showed enhanced structural quality as suggested by the reduction in the intensity of the defect-related emissions. Prolonging the deposition time beyond 20 min does not improve the properties of the grown thin films. Metal-semiconductor-metal photodetectors were fabricated based on the synthesized CdS thin films. Current–voltage measurements showed superior characteristics of the fabricated photodetectors based on CdS thin films grown at deposition times of 10 and 20 min compared to those based on CdS thin film grown at a deposition time of 30 min. Photodetector based on CdS thin film grown at a deposition time of 20 min exhibited enhanced photodetection properties. The device showed the fastest response time of 9 ms with a photosensitivity of 1440% to 500 nm chopped light at an applied bias of –1 V. Whereas, photodetector based on CdS thin film grown at a deposition time of 30 min showed the longest response and recovery times of 35 and 42 ms, respectively with a photosensitivity of 51.70%. Photodetection measurements revealed that schottky contact based devices have a superior performance than those with ohmic contact-based devices

Radio Resource Management in NB-IoT Systems:Empowered by Interference Prediction and Flexible Duplexing

NB-IoT is a promising cellular technology for enabling low cost, low power, long-range connectivity to IoT devices. With the bandwidth requirement of 180 kHz, it provides the flexibility to deploy within the existing LTE band. However, this raises serious concerns about the performance of the technology due to severe interference from multi-tier 5G HetNets. Furthermore, as NB-IoT is based on HD-FDD, the symmetric allocation of spectrum band between the downlink and uplink results in underutilization of resources, particularly in the case of asymmetric traffic distribution. Therefore, an innovative RRM strategy needs to be devised to improve spectrum efficiency and device connectivity. This article presents the detailed design challenges that need to be addressed for the RRM of NB-IoT and proposes a novel framework to devise an efficient resource allocation scheme by exploiting cooperative interference prediction and flexible duplexing techniques