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 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

Optical Variability, Rotation Period and Inclination Angle of the M9.5 dwarf BRI 0021-0214

We report $I$-band photometric observations of the radio-detected M9.5 dwarf BRI 0021-0214, obtained with the Galway Ultra Fast Imager (GUFI) on the 1.8m Vatican Advanced Technology Telescope VATT at Mt. Graham International Observatory, Arizona. In total, 19 hours of observations over a 73 day baseline were obtained. BRI 0021-0214 was shown to exhibit modulated emission with a period of $3.052 \pm 0.004$ hours with a mean amplitude variability of 0.0044 mag. When combined with rotational velocity data obtained from previous work, our newly discovered rotation period gives an inclination angle of 51.7$^{+5.0}_{-4.5}$ degrees for the rotation axis of BRI 0021-0214 relative to our line of sight. Previous studies have reported that the most plausible cause for optical variability from this dwarf is a consequence of suspended co-rotating dust clouds in its atmosphere. However reports of enhanced H$_{\alpha}$ and intermittent coherent radio emission suggest the possibility of auroral activity in its magnetosphere. Further, more coordinated multiwavlength observations of this dwarf could fully resolve the nature of this elusive rapid-rotator object's observational properties

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

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

Alignment of Construction Procurement Strategies for the Effective Implementation of BIM in the UAE

The effective diffusion of Building Information Modelling (BIM) presents strong potential to evolve the productivity and performance of the construction industry. Implementing BIM effectively requires significant changes in the construction business practices to improve communication, collaboration and sharing information among team members in design, construction and operating phases. The aim of this paper is to investigate the required reformation of current procurement methods in the UAE to enable the effective diffusion of BIM. The paper will present a conceptual framework which illustrates the needed changes in procurement methods being change in the relationship among participants, change in the contractual agreements, sharing the risks and rewards among stakeholders, early involvement of stakeholders, and involvement of new participants. The paper will report the findings of the analysis of four case studies of companies with vast experience in projects that adopted BIM and how it has impacted the procurement approaches adopted. The research findings have articulated that in order to implement BIM process effectively, it is critical for the UAE construction industry to adopt more collaborative relationships and share the risks and rewards among the participants. The findings show that the most important requisite change is for the key players at design stage to collaborate to create an effective BIM model that will save time and cost. Furthermore, contracts should oblige the participants to adopt BIM, identify the level of development in each stage and determine the responsibilities and intellectual property rights of each stakeholder

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

Factors Influencing the Selection of Delay Analysis Methods in Construction Projects in UAE

Several delay analysis methods (DAMs) have been developed and used in the construction industry in order to analyse the causes and effects of delay events. In this research, a number of commonly used DAMs, in the specific context of UAE, are investigated by exploring the factors influencing their selection decisions as well as the process of making such a decision. A total of eight expert respondents from five different projects in the UAE were selected who provided critical insight into the decision making process adopted in practice to select a DAM. The individual project case analysis as well as the cross case analysis helped to identify a number of factors that influence the selection of DAMs in UAE projects. Some of the main identified factors were the attitude of the client, experience of the delay analyst, reputation and impartiality of the delay analyst, complexity of the project, and cost and timing of performing the analysis. The research argues that such an important decision process that can have a serious impact on the success of a commercial venture requires individual organisations to develop and adopt clear guidelines on how such decisions are made to protect its commercial interests