| 1 |
Author(s):
Abdullahi, Hamza Sulayman.
Page No : 1-9
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Effect of seed points on the geometric and mechanical properties of Voronoi foams
Abstract
Foams are cellular materials with unique mechanical properties. The geometric properties of these structures have been proved to be responsible for their unique mechanical properties. In the process of modeling and simulation, reproducing those geometric properties accurately is still a challenge to researchers. This paper provides details on the geometric modeling techniques used to model the foams and investigates the effects of the initial seed points on the geometric and mechanical properties. Unit cell repetition methods such as Kelvin cell, Gibson-Ashby cell as well as randomly generated models such as Poisson Voronoi, Hardcore Voronoi, and Laguerre Voronoi were all investigated and their effectiveness in reproducing the geometric properties of the foams and predicting the elastic properties is demonstrated.
| 2 |
Author(s):
Tasiu Ashiru Sulaiman, Abdulhamid Aliyu Ozovehe, Ibrahim Aliyu.
Page No : 10-18
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SUITABILITY OF USING BUSH PEBBLE (COARSE AGGREGATE) IN THE PRODUCTION OF CONCRETE
Abstract
This study is aimed at evaluating the suitability of using Bush pebble (coarse aggregate) sourced from the Kangiwa village in Kebbi Niger State, Nigeria in the production of concrete with 1:2:4 and 0.45, 0.55 and 0.65 as a mix ratio and water cement ratios respectively. The coarse aggregate (Bush pebble) used has a nominal size of 20 mm with a specific gravity of 2.65 and a bulk density of 1345.1 kg/m3. The results of workability (slump) and compaction factor show that as the water-cement ratio increases the workability (slump) and compaction factor increase. Additionally, the densities of concrete produced with different water-cement ratios fall within the limits of 2200 kg/m3 to 2600 kg/m3. On the other hand, the compressive strength of concrete produced with Bush pebble increases as the curing age and water-cement ratio increase. The regression model developed for the compressive strength of concrete is adequate for predicting the compressive strength of concrete produced with Bush pebble (aggregate). It was concluded that, based on different tests carried out, the Bush pebble (aggregate) can be used in the production of concrete as a substitute for normal coarse aggregate.
| 3 |
Author(s):
Nasiru Bello Kadandani.
Page No : 19-27
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EXPERIMENTAL IMPLEMENTATION OF SORTING ALGORITHM BASED VOLTAGE BALANCING OF MODULAR MULTILEVEL CONVERTER
Abstract
Of paramount important to the proper operation of modular multilevel converter (MMC) is the submodule (SM) capacitor voltage balancing. Two major approaches proposed to achieve this task are distributed method and centralized method. This paper presents an experimental implementation of the centralized SM capacitor voltage balancing control strategy in MMC based on sorting algorithm. The concept was experimentally demonstrated on a laboratory prototype MMC with four SMs per arm. The results show that the SM capacitor voltages are properly balanced and regulated to their reference values. Further, the resultant output voltage and current waveforms exhibit perfect harmonic performance with fundamental switching frequency; thus confirming the effectiveness of the control method.
| 4 |
Author(s):
Nasiru Bello Kadandani.
Page No : 28-39
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ON EXPLORING THE POWER QUALITY ENHANCEMENT CAPABILITY AND OTHER ANCILLARY FUNCTIONALITIES OF SOLID STATE TRANSFORMER IN THE DISTRIBUTION GRIDS
Abstract
Nowadays, the distribution grids are facing technical challenges due to the increased connection of sizeable loads like electric vehicle (EV) charging stations as well as large penetration of distributed renewable energy resources (DRERs) notably wind energy conversion system (WECS) and solar power plant (SPP), thus resulting in some operational issues in the form of power quality disturbance, reliability issues and grid congestion. To this extent, solid state transformer (SST) has been envisioned as a promising device for improving the power quality, providing a bidirectional power flow capability as well as ensuring a smooth and safe way of interfacing DRERs with the distribution grid. This paper reviews the basic power quality parameters in electrical power system, the role of SST in power quality improvement as well as some other ancillary services that SST can offer to the grid which cannot be achieved with the conventional line frequency transformer (LFT).
| 5 |
Author(s):
Muhammad Buhari, Jorge Angarita Marquez, Geev Mokyryani.
Page No : 40-48
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OPTIMIZATION OF DISTRIBUTION SYSTEMS INCORPORATING DISTRIBUTED GENERATION AND BATTERY ENERGY STORAGE SYSTEMS
Abstract
This paper proposes a novel a multi-stage stochastic problem to minimize the cost of the Distribution System (DS) including the Distribution Network (DN) and customer costs. This paper proposes a central planning approach where the decision variables are the sizing, siting, and operation of Battery Energy Storage Systems (BESS), the sizing and siting of Distributed Generation (DG) and capacity of the distribution lines. The algorithm estimates the optimal BESS’s energy storage capacity as well as the maximum hourly delivery capacity. The customers’ objective function is the capacity and energy payments minus the saving and revenue from DG. The Distribution Network Operator’s (DNO) goal is to minimize the cost of the distribution network and BESS’s investments and operational costs. Since the model has a long-term approach, the paper presents the implementation of Expected Value as decision criterion to handle the uncertainty. The impact of the remuneration rules for DG on customers’ and DN’s cost are calculated. The results show that the incorporation of DG brings important benefits to the customers while BESS provide modest improvements.
