Reliable indoor optical wireless communication in the presence of fixed and random blockers

The advanced innovation of smartphones has led to the exponential growth of internet users which is expected to reach 71% of the global population by the end of 2027. This in turn has given rise to the demand for wireless data and internet devices that is capable of providing energy-efficient, reliable data transmission and high-speed wireless data services. Light-fidelity (LiFi), known as one of the optical wireless communication (OWC) technology is envisioned as a promising solution to accommodate these demands. However, the indoor LiFi channel is highly environment-dependent which can be influenced by several crucial factors (e.g., presence of people, furniture, random users' device orientation and the limited field of view (FOV) of optical receivers) which may contribute to the blockage of the line-of-sight (LOS) link. In this thesis, it is investigated whether deep learning (DL) techniques can effectively learn the distinct features of the indoor LiFi environment in order to provide superior performance compared to the conventional channel estimation techniques (e.g., minimum mean square error (MMSE) and least squares (LS)). This performance can be seen particularly when access to real-time channel state information (CSI) is restricted and is achieved with the cost of collecting large and meaningful data to train the DL neural networks and the training time which was conducted offline. Two DL-based schemes are designed for signal detection and resource allocation where it is shown that the proposed methods were able to offer close performance to the optimal conventional schemes and demonstrate substantial gain in terms of bit-error ratio (BER) and throughput especially in a more realistic or complex indoor environment. Performance analysis of LiFi networks under the influence of fixed and random blockers is essential and efficient solutions capable of diminishing the blockage effect is required. In this thesis, a CSI acquisition technique for a reconfigurable intelligent surface (RIS)-aided LiFi network is proposed to significantly reduce the dimension of the decision variables required for RIS beamforming. Furthermore, it is shown that several RIS attributes such as shape, size, height and distribution play important roles in increasing the network performance. Finally, the performance analysis for an RIS-aided realistic indoor LiFi network are presented. The proposed RIS configuration shows outstanding performances in reducing the network outage probability under the effect of blockages, random device orientation, limited receiver's FOV, furniture and user behavior. Establishing a LOS link that achieves uninterrupted wireless connectivity in a realistic indoor environment can be challenging. In this thesis, an analysis of link blockage is presented for an indoor LiFi system considering fixed and random blockers. In particular, novel analytical framework of the coverage probability for a single source and multi-source are derived. Using the proposed analytical framework, link blockages of the indoor LiFi network are carefully investigated and it is shown that the incorporation of multiple sources and RIS can significantly reduce the LOS coverage blockage probability in indoor LiFi systems

Methods for Enhancing Recovery of Heavy Crude Oil

The methods of enhancing recovery of heavy crude oil explore the importance of enhanced oil recovery and how it has grown in recent years due to the increased needs to locate unconventional resources such as heavy oil, shale, and bitumen. Unfortunately, petroleum engineers and managers are not always well-versed in the enhancement methods available when needed or the most economically viable solution to maximize their reservoir’s productivity. Various recovery methods have been explored to extract heavy oil from deep reservoirs or oil spills. This chapter summarizes the details of methods, namely nanoparticle technology, carbon dioxide injection, thermal recovery and chemical injection, which include the methodology as well as the findings

Oil–Water Separation Techniques for Bilge Water Treatment

Discharging accumulated bilge water from the ship is very important in order to maintain its stability and safety. However, the bilge water that contains contaminants, including waste oils and oily wastes, must be treated prior discharging to the sea. The International Convention for the Prevention of Pollution from Ships (MARPOL) has set strict oil discharge limit in order to minimize sea pollution. Thus, an efficient oil–water separator must be installed to separate the oil from the bilge water. This chapter introduces and discusses the working mechanisms, as well as advantages and disadvantages of the available oil–water separation techniques for bilge water treatment, which include gravitational, centrifugation, flotation, coagulation and flocculation, biological processes as well as absorption and adsorption

Vacuum-assisted block freeze concentration studies in cheese whey and its potential in lactose recovery

Block freeze concentration (BFC) is considered an emerging technology which allows the acquiring of high quality organoleptic products, due to the low temperatures employed. In this study we have outlined how the vacuum-assisted BFC of whey was investigated. The effects of vacuum time, vacuum pressure, and the initial solids concentration in whey were studied. The results obtained show that the three variables significantly affect each of the following parameters analysed: solute yield (Y) and concentration index (CI). The best Y results were obtained at a pressure of 10 kPa, 7.5°Bx, and 60 min. For CI parameter, the highest values were given at 10 kPa, 7.5°Bx, and 20 min, respectively. In a second phase, by applying the conditions that provide higher solute yield to three different types of dairy whey, Y values of 70% or higher are reached in a single step, while that the CI of lactose are higher than those of soluble solids. Therefore, it is possible to recover, in a single step, at least 70% of the lactose contained in the initial whey samples. This suggests that vacuum-assisted BFC technology may be an interesting alternative for the recovery of lactose contained in whey.This research received no external funding. The APC was financed by AGRUPS-2022 at Universitat Politècnica de Catalunya (UPC) and SGR-Cat 2021 of Departament de Recerca i Univer- sitats (Generalitat de Catalunya)Objectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesPostprint (published version

Optimal distributed generation in green building assessment towards line loss reduction for Malaysian public hospital

This paper presents an optimization approach for criteria setting of Renewable Distributed Generation (DG) in the Green Building Rating System (GBRS). In this study, the total line loss reduction is analyzed and set as the main objective function in the optimization process which then a reassessment of existing criteria setting for renewable energy (RE) is proposed towards lower loss outcome. Solar photovoltaic (PV)-type DG unit (PV-DG) is identified as the type of DG used in this paper. The proposed PV-DG optimization will improve the sustainable energy performance of the green building by total line losses reduction within accepted lower losses region using Artificial bee colony (ABC) algorithm. The distribution network uses bus and line data setup from selected one of each three levels of Malaysian public hospital. MATLAB simulation result shows that the PV-DG expanding capacity towards optimal scale and location provides a better outcome in minimizing total line losses within an appropriate voltage profile as compared to the current setting of PV-DG imposed in selected GBRS. Thus, reassessment of RE parameter setting and the proposed five rankings with new PV-DG setting for public hospital provides technical justification and give the best option to the green building developer for more effective RE integration

Photovoltaic-integrated review and expansion need in green building landscape for bridging the Malaysian RE policy

A literature review is presented specifically on the photovoltaic (PV) as a distributed generation (DG) integration approach and the extensiveness through renewable energy (RE) assessment criteria in current green building rating system (GBRS) to: delineate for further classification in terms of installed-capacity; identify the RE applications’ intent / aim; and recommendation for PV-type DG (PV-DG) expansion needs. The paper aims to close the gap in knowledge, by an empirical review of current RE assessment criteria and to portray the expected evolution of RE for higher installed-capacity in ensuring the government key achievement can be achieved. In considering the expansion needs in GBRS, the optimal technique for PV-DG expansion-limit would serve as a conceptual bridge between expanding mechanism and realization of the Malaysian most recent RE policy specifically on the drastically increment of RE quota. These can be achieved since various DG optimization case studies have been presented and overcome with the improvement impact on the test system, in term of power loss reduction, increased efficiency and optimal cost outcome. Future analysis as well as research direction are proposed and linked with some of the previous optimization reviews in recent literature

Photovoltaic Expansion-Limit through a Net Energy Metering Scheme for Selected Malaysian Public Hospitals

This paper presents an optimization approach in determining the expansion-limit of Renewable Distributed Generation (DG) capacity through a Net Energy Metering (NEM) scheme specifically for selected Malaysian public hospitals. In this study, the total line loss reduction was analyzed and set as the main objective function in the optimization process where an acceptance region for DG extensiveness was proposed via the lower total line loss outcome value. Solar photovoltaic (PV)-type DG unit (PV-DG) was identified as the type of DG used in this paper. Artificial Bee Colony (ABC) algorithm was chosen to alleviate such PV-DG optimization. The distribution network uses a bus and line data setup from the three selected Malaysian public hospitals prior to three different levels, i.e., National, State, and District level hospitals. MATLAB simulation result showed the PV-DG expansion capacity towards bigger scale and location bounded by the U-trajectory shape theory which resulted in a contradiction between NEM current maximum capacity requirement and actual PV-DG expansion-limit. These limitations were also found to be different among three different level hospitals, and the expansion-limit was tailored by their own distribution network parameters. Thus, this paper provides technical justification and gives the best option to the renewable energy (RE) developer for more effective PV-DG integration through the utilization of a NEM scheme. The importance of the study is portrayed in-depth towards achieving a more sensible and accurate way of estimating the outcome. This will encourage developers, building owners, and users in participating towards achieving potential benefits both in monetary and power system reliability improvement, specifically for Malaysian public hospital applications

Renewable energy performance of the green buildings: key-enabler on useful consumption yield.

Malaysia’s Eleventh Plan started to encourage green building developments and green industries to stimulate green growth. Eventually, the Malaysian government had launched a new commitment to accelerate the green and efficient energy sector and revised the quota of Renewable Energy (RE) towards higher capacity for electricity generation. These scenarios had highlighted the latest commitment of the Malaysian government to implement both green building development and concurrently, streamline the additional quota for RE generation. Due to this, the evolution of the requirement of RE-based Distributed Generation (DG) in the green building development for higher installed-capacity was expected to occur in ensuring the government key achievement becomes more visible. This study focuses on measuring the expanded-capacity performance of the Solar Photovoltaic (PV)-type DG unit (PV-DG) through the Green Building Rating System (GBRS), particularly on the useful energy consumption yield for load and total line loss minimization. Previous work has conducted a MATLAB simulation on a PV-DG capacity expansion guided by the Net Energy Metering (NEM) specification considering the total line loss minimization as the main objective function. These results are being adopted to obtain the ratio of useful energy consumption from the generated PV-DG through the selected distribution network. Consequently, the Performance Ratio (PR) - as the internationally recognized formulation for a complete PV-DG system - is proposed to be revolutionized towards extended version, considering the specific total line losses minimization, via the formed of the proposed ratio

Improving antioxidant scavenging effect of fruit peel waste extracts and their applicability in biodiesel stability enhancement

The increasing popularity of fruit peel extracts as effective sources of natural antioxidants is primarily attributed to their affordability, easy availability, and high phenolic contents that readily dissolve in solutions. However, most natural antioxidants demonstrate a lesser free radical scavenging effect when applied in mono blends compared to their synthetic counterparts. To address this problem, this work aims to improve the antioxidant capacities of palm fruit, banana, and mango peel liquid extracts recovered using supercritical fluid extraction (SFE). Firstly, a reverse-phase high-performance liquid chromatography (RP-HPLC) was used to isolate three (3) target bioactive compounds from the extracts, whose estimated quantities ranged between 1.2983–4.6841, 1.1469–3.6987, and 0.0254–0.0489 mg/g for quercetin, beta-carotene, and gallic acid respectively. Subsequently, blends of the recovered extracts were formulated in mono, binary, and ternary dosage ratios (S.1–S.10) to assess their free radical scavenging efficiency (RSE) in terms of inhibitory concentration at 50% (IC50) using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, total phenolic content (TPC), total flavonoid content (TFC), and total carotenoid content (TCC). Based on the results obtained, the highest RSE was exhibited by the ternary blend (S.9), with an IC50 value of 76.21 ± 032 µg/mL and a TPC value of 242.38 ± 0.26 mg gallic acid equivalent (GAE/g). The fastest kinetics for the extracts’ reaction with DPPH corresponding to a rate constant (K) of 1.2351 M−1.min−1 and activation energy (Ea) of 0.55 KJ/mol were presented by the same sample blend (S.9), indicating the ease of hydrogen atom release for radical scavenging. Finally, the peel extracts demonstrate an improved antioxidative performance by prolonging the biodiesel’s induction period of the extracts-blended samples as obtained from Rancimat analysis