Properties of High-Performance Concretes made of Black Sand at High Temperature

To modify high-performance concrete (HPC) fireproofing properties, black sand (BS) was partially substituted as fine aggregate at various levels. This study aims at evaluating the BS reliability in improving HPC durability properties for various construction applications based on its unique heavy minerals. To achieve this, five HPC series blends were setup to substitute fine aggregate independently with BS. Substitution percentages ranged from 15 to 100% with consistent supplementary cementing materials (SCMs) proportion for each gathering. Tests were performed to assess compressive strength before and after fire exposure under various temperatures of 250, 500 and 750 °C at different curing age. Generally, blending FA with BS was better than using SF with BS. Utilizing BS in the range of 15 to 60% as fine aggregate with 10% FA improves HPC fire-insulating properties. Besides, Z1 SEM analysis observed homogenously and compacted HPC microstructure at 250 and 500 °C. Doi: 10.28991/cej-2021-03091634 Full Text: PD

Enhancing the evaporative cooling performance of fan-pad system using alternative pad materials and water film over the greenhouse roof

Greenhouse technology is a viable option for sustainable crop production in the regions of adverse climatic conditions.  During hot seasons the heat input to a greenhouse causes the internal temperature to exceed its optimal value.  The present study was devoted to construct an evaporative cooling system to reduce heat stress inside a greenhouse.  Two identical small-scale greenhouses were designed, constructed, and installed on an open roof of a domestic house.  The two greenhouses were cooled using fan-pad system.  In addition, a thin water film was applied on the roof of one greenhouse to study the effect of roof water film and fan-pad (combined system) on the cooling performance.  The two cooling systems were compared under the same condition.  Three new evaporative cooling pads represented by Cryperus Alopecuroides Rottb (Samar), Cyerus Alternifolius (Purdy) and Cyperus Rotundus l (Nut-grass or Se'd) were adapted and evaluated.  Three pad face air velocities ranged between 0.45 and 1.01 m s-1 and two thicknesses of 10 and 15 cm were used in the investigation of the cooling performance criteria.  Results showed that the proposed cooling pads in the suggested evaporative cooling systems were able to maintain acceptable microclimatic conditions for greenhouse models.  Se'd pad material proved more efficiency in temperature reduction.  It was revealed that the temperature inside the greenhouse operated under the combination of roof water flow and fan-pad system was less than that for fan-pad greenhouse by about 1.1 to 5.44° C in the morning and afternoon respectively.  The air relative humidity was increased due to humid effect provided by cooling system which protects crops from excessive transpiration and crop damage.  The daily average cooling efficiencies of 88.4, 83.1 and 79.6% were obtained for Se'd, Purdy and Samar, respectively during testing days inside the combined system at 15 cm pad thickness and 0.45 m s-1 pad face air velocity.  The Se'd pad material showed the highest efficiency as compared to other pad materials and could be used as an alternative pad material.   Keywords: greenhouse, evaporative cooling, fan-pad system, pad material, roof water flo

Applications of AI and IoT for Advancing Date Palm Cultivation in Saudi Arabia

Date palm cultivation is an essential part of Saudi Arabia’s economy. However, it faces several challenges: water scarcity, improper farm management, pests and diseases, inadequate farming practices, processing and marketing, and labor shortages. Artificial intelligence (AI) and the Internet of Things (IoT) can help enrich crop management, enable predictive analytics, increase efficiency, and promote sustainability in date palm cultivation. Recently, interest in this sector has begun by applying the latest precision engineering technologies integrated with AI and IoT techniques to address these challenges. This chapter aims to provide an overview of the applications of AI and IoT-based technologies, such as sensors, ML algorithms, and data analytics, and their potential benefits and challenges in supporting date palm cultivation in Saudi Arabia. Specifically, the applications of AI and IoT in smart precision irrigation, smart systems, cold storage management, pest infestation prediction, and date fruit quality optimization. In addition, the potential economic and environmental benefits of using AI and IoT in date palm cultivation in Saudi Arabia and the challenges that need to be addressed to realize these benefits fully. The chapter provides insight into the latest developments and future directions for AI and IoT in date palm cultivation, providing valuable information for researchers and policymakers

Grid-connected photovoltaic power systems: Technical and potential problems--A review

Traditional electric power systems are designed in large part to utilize large baseload power plants, with limited ability to rapidly ramp output or reduce output below a certain level. The increase in demand variability created by intermittent sources such as photovoltaic (PV) presents new challenges to increase system flexibility. This paper aims to investigate and emphasize the importance of the grid-connected PV system regarding the intermittent nature of renewable generation, and the characterization of PV generation with regard to grid code compliance. The investigation was conducted to critically review the literature on expected potential problems associated with high penetration levels and islanding prevention methods of grid tied PV. According to the survey, PV grid connection inverters have fairly good performance. They have high conversion efficiency and power factor exceeding 90% for wide operating range, while maintaining current harmonics THD less than 5%. Numerous large-scale projects are currently being commissioned, with more planned for the near future. Prices of both PV and balance of system components (BOS) are decreasing which will lead to further increase in use. The technical requirements from the utility power system side need to be satisfied to ensure the safety of the PV installer and the reliability of the utility grid. Identifying the technical requirements for grid interconnection and solving the interconnect problems such as islanding detection, harmonic distortion requirements and electromagnetic interference are therefore very important issues for widespread application of PV systems. The control circuit also provides sufficient control and protection functions like maximum power tracking, inverter current control and power factor control. Reliability, life span and maintenance needs should be certified through the long-term operation of PV system. Further reduction of cost, size and weight is required for more utilization of PV systems. Using PV inverters with a variable power factor at high penetration levels may increase the number of balanced conditions and subsequently increase the probability of islanding. It is strongly recommended that PV inverters should be operated at unity power factor.Grid-connected photovoltaic Penetration levels of grid tied PV Inverter technology Islanding detection methods

Developing the NIS solid density hydrostatic weighing system up to 20 kg

This paper presents a developed design and construction to improve the performance and increasing the density measuring capability of the previous Hydrostatic Weighing Apparatus (HWA-NIS) at the National Institute of Standards (NIS) up to 20 kg. The previous (HWA-NIS) has been constructed up to 10 kg on 2014. The 2-Positions mass handler in the previous (HWA) was developed with 4-Positions pentagon shape to be able to make handling for individual masses in a group at once, when transferring the traceability from the primary standard “the Silicon Sphere” to the standard masses in the density scale weighing process. The weighing pan in the previous (HWA) was developed with four suspension wires with a diameter of 0.3 mm each, leads to reduce the surface tension affect on the measurement uncertainty by factor four times. The density of the standard masses in the range from 2 kg up to 20 kg were measured with an improved expanded uncertainty from 0.150 kg/m3 to 0.078 kg/m3 respectively due to reducing the effect of surface tension via the developed design of the weighing pan

A review of renewable energy technologies integrated with desalination systems

Energy is an essential ingredient of socio-economic development and economic growth. Renewable energy provides a variable and environmental friendly option and national energy security at a time when decreasing global reserves of fossil fuels threatens the long-term sustainability of global economy. The integration of renewable resources in desalination and water purification is becoming increasingly attractive. This is justified by the fact that areas of fresh water shortages have plenty of solar energy and these technologies have low operating and maintenance costs. In this paper an attempt has been made to present a review, in brief, work of the highlights that have been achieved during the recent years worldwide and the state-of-the-art for most important efforts in the field of desalination by renewable energies, with emphasis on technologies and economics. The review also includes water sources, demand, availability of potable water and purification methods. The classification of distillation units has been done on the basis of literature survey till today. A comparative study between different renewable energy technologies powered desalination systems as well as economics have been done. The real problem in these technologies is the optimum economic design and evaluation of the combined plants in order to be economically viable for remote or arid regions. Wind energy technology is cheaper than the conventional ones, and used extensively around the world. The slow implementation of renewable energy projects especially in the developing countries are mostly due to the governments subsides of conventional fuels products and electricity. The economic analyses carried out so far have not been able to provide a strong basis for comparing economic viability of each desalination technology. The economic performances expressed in terms of cost of water production have been based on different system capacity, system energy source, system component, and water source. These differences make it difficult, if not impossible, to assess the economic performance of a particular technology and compare it with others. Reverse osmosis is becoming the technology of choice with continued advances being made to reduce the total energy consumption and lower the cost of water produced.Renewable energy Water sources Desalination technologies Reverse osmosis Economics

Design and Validation of an Automated Hydrometers Calibration System

Abstract: Liquid density measurement is an important activity in many laboratories. Usually hydrometers are used to measure the density of liquids in the range from 600 kg/m 3 up to 1850 kg/m 3 . For the purpose of metrological traceability of Hydrometers with the international density reference standards a calibration system has been designed, constructed and validated at the National Institute for Standards, NIS, Egypt. The system covers the range from 500 kg/m 3 up to 2000 kg/m 3 . The system is automatically operated for the intended measurements and calibrations using hydrostatic weighing (Cuckow's method). Distilled water was used as a reference liquid. Finite element analysis using (ABAQUS) software for 3D has been used to check the stress, deformation, rigidity, stability as well, to optimize the design of the system. A laser light source and two linear encoders are used to position the standard liquid surface at the hydrometer scale mark during calibration process. For accurate measurements of scale mark position, an image processing technique combined with a high resolution CCD camera for capture the reading during calibration is used. Lab VIEW program is designed to processing the reading from measurement instruments in a fully automated mode. The calibration results present an expanded uncertainty (with a coverage factor of k= 2) less than 100 ppm. The apparatus's performance has been validated by comparing the output results of the system versus Laboratoire National de Metrologie et d'Essais "LNE" calibration certificates of 3 standard hydrometers

Solving the container pre-marshalling problem using variable length genetic algorithms

<p>In container terminals, the yard area consists of a set of blocks, which consists of a set of bays. Each bay consists of a set of stacks, which consists of a set of tiers. In the container pre-marshalling problem, an initial layout of a bay is converted to a final desired layout. The final layout follows the given loading schedule of this bay. This has a direct impact on the most important container terminal performance measure: the vessel loading time. The deviation between the current layout and the desired layout is expressed by the value of the mis-overlays. The objective of the pre-marshalling problem is to eliminate the mis-overlays with the minimum number of container movements. In this article, a variable chromosome length genetic algorithm was applied to solve the problem. The results of the new solution approach were compared against benchmark instances and the results were remarkably better.</p