Gehan Amaratunga

University of Cambridge | Cam · Department of Engineering

Dynamic state estimation (DSE) of the power system is one of the most important means to ensure a safe and stable operation of the power system. However, the electromagnetic field environment, communication noise and equipment failure often lead to the appearance of non‐Gaussian noise and bad data, which ultimately cause performance degradation of...

The thermal conductivity measurements of graphene nanoplatelets (GNP) loaded mineral oil suspensions are obtained using an unconventional custom-made Transient Hot-Wire setup using tungsten. The presence of a few layers of graphene in the prepared GNP using a single-step ultrasonication of graphite microparticles without the use of a surfactant is...

With the rapid development of the Internet of Things (IoTs), wearable sensors are playing an increasingly important role in daily monitoring of personal health and wellness. The signal-to-noise-ratio has become the most critical performance factor to consider. To enhance it, on the one hand, good sensing materials/devices have been employed; on the...

A photodiode consisting of nanopillars of thin-film silicon p-i-n on an array of vertically aligned carbon nanotubes (CNTs) with a noncontinuous cathode electrode is demonstrated. The structure exploits the intrinsic enhancement of the CNTs electric field, which leads to reduction in the photodiodes operating voltage and response time and enhanceme...

Solar energy is potentially the largest source of renewable energy for providing electrical power for human society. However, significant advances are required to make photovoltaic technologies have a low-carbon footprint in manufacture, be environmentally friendly at the end of their lives through recyclability, and be biodegradable. Here we repor...

Background Diabetes Mellitus (DM) can appear due to the absence of insulin (DM1- type 1) or poor response of cells to insulin (DM2-type 2). Even though DM1 cannot be controlled using general treatments, DM2 can be easily controlled or prevented using pharmaceuticals, nutraceuticals, or dietary practices. Ceylon cinnamon (Cinnamomum zeylanicum) is o...

For state estimation of dynamic electro-thermal gas coupled systems, measurements usually assume that the measurement noise obeys a Gaussian distribution. The extended Kalman filter (EKF) and the unscented Kalman filter (UKF) are some of the widely used estimation methods in state estimation. However, the measurement noise does not always follow Ga...

The distribution of measurement noise applied in practical power system state estimation (PSSE) can deviate from the assumed Gaussian model and the performance of an estimator becomes bad if the Gaussian model is still used. This paper proposes a new distributed robust PSSE method for multi-area power systems. The non-Gaussian model is utilized to...

Aims The present study examines the atomic-scale structures of Graphene Oxide (GO) and Reduced Graphene Oxide (RGO). Background Electron microscopic studies on Sri Lankan vein graphite are considerably less; hence, this study focuses on the atomic-scale study of Sri Lankan vein graphite, using advanced electron microscopic techniques. Objective T...

For power system state estimation, the measurement noise is usually assumed to follow the Gaussian distribution and the widely used estimator is the weighted least squares (WLS). However, the Gaussian distribution assumption is not always true and the performance of WLS becomes bad when the measurement noise is non-Gaussian. In this paper, a new di...

Electrolytic batteries with the anode or cathode formed by electro-deposition from the electrolytes show promising potential for simplifying the fabrication process of flexible and micro-size rechargeable batteries. Thin flexible zinc batteries with both anode and cathode electro-deposited simultaneously are demonstrated and investigated here. We f...

Uncertainties such as abnormal system inputs, strong model nonlinearities, outliers and impulsive noise unavoidably exist in the power system dynamic state estimation (DSE). The existing Kalman filter-based DSE methods cannot deal with the uncertainties well and can be improved further. In this paper, a robust DSE method based on the maximum correl...

An integrated textile electronic system is reported here, enabling a truly free form factor system via textile manufacturing integration of fiber-based electronic components. Intelligent and smart systems require freedom of form factor, unrestricted design, and unlimited scale. Initial attempts to develop conductive fibers and textile electronics f...

Carbon nanostructure synthesis has been extensively researched recently due to its potential applications in energy storage, drug delivery, imaging, composite materials, field emitters, Nano-electronic devices, EMI shielding, hydrogen storage Nano tanks, functional polymers, sensor materials, and material reinforcement. Vapor deposition is the most...

The distribution of measurement noise is usually assumed to be Gaussian in the optimal phasor measurement unit (PMU) placement (OPP) problem. However, this is not always accurate in practice. This paper proposes a new OPP method for smart grids in which the effects of conventional measurements, limited channels of PMUs, zero-injection buses (ZIBs),...

The interface between the polymer and nanoparticle has a vital role in determining the overall dielectric properties of a dielectric polymer nanocomposite. In this study, a novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO2 nanoparticles surface modified by hydrogen plasma treatments was s...

This paper proposes a new method for the placement of the important synchrophasor sensors, the Distribution-level Phasor Measurement Units (DPMUs). The new objective function and constraints are developed to achieve the minimization of distribution system state estimation error, in the presence of the limited number of DPMUs, the zero injection bus...

We propose a computational design framework to design the architecture of a white lighting system having multiple pixelated patterns of electric-field-driven quantum dot light-emitting diodes. The quantum dot of the white lighting system has been optimised by a system-level combinatorial colour optimisation process with the Nelder-Mead algorithm us...

Quantum dots (QDs) are an emerging class of photoactive materials that exhibit extraordinary optical features. Due to the availability of narrowband emitted light from QDs, they can be used to pave the way for next-generation light-emitting devices, especially in the development of LEDs and lasers. Over recent years solution-processed colloidal QDs...

A highly controllable, green, and rapid strategy is demonstrated for fabricating of highly sensitive non-enzymatic glucose sensing platforms. Carbon nanohorns (CNHs) were decorated onto the screen-printed electrodes. Binary nickel-cobalt sulfide (NiCo-S) nanosheets (NSs) were then deposited on CNH-casted electrodes by a facile and scalable method....

Various dyeing techniques are utilised at dyeing different types of fabrics and current study discuss the possibility of using a single dye bath for the given purpose. The current study utilised a radio frequency glow discharge plasma source maintained at near atmospheric conditions (around 200 mbar) in nitrogen and air environments to treat cotton...

In a time where global agricultural stability is facing unprecedented challenges due to growing population, climate change, and emerging pandemics, the development of advanced organic-inorganic functional nanohybrids as advanced fertilizers could contribute significantly to meeting these challenges. They hold the potential of reducing overall ferti...

In realistic power system state estimation, the distribution of measurement noise is usually assumed to be Gaussian while many researcher have verified that it can be non-Gaussian. In this paper, a new robust state estimator based on exponential absolute value function is proposed to address the non-Gaussian measurement noise and outliers. The infl...

Smart textiles consist of discrete devices fabricated from—or incorporated onto—fibres. Despite the tremendous progress in smart textiles for lighting/display applications, a large scale approach for a smart display system with integrated multifunctional devices in traditional textile platforms has yet to be demonstrated. Here we report the realisa...

A nanotechnology based approach to improve the anticancer of XLAspP2-RA, against muscle rhabdomyosarcoma (RD) is reported. The XLAspP2-RA was successfully synthesized, and the structure was confirmed by ¹H NMR spectroscopy. Loading of XLAspP2-RA into APTES modified halloysite nanotubes and Graphene Oxide are confirmed by FT-IR spectroscopy. The enc...

Even though the noise model applied in power system dynamic state estimation (DSE) is usually assumed to be Gaussian, this is not the case due to the unknown system inputs, influence from the communication channel noise, and the outliers generated by phasor measurement units (PMUs). In this article, a robust power system DSE method combining a robu...

Phasor measurement units (PMUs) are becoming more popular in power systems and most of the distributed state estimation methods are based on the Gaussian measurement noise assumption. However, the PMU measurement noise has been demonstrated to be non-Gaussian. This article presents a distributed multiarea state estimation approach based on the quad...

Device architectures of patterned-, stacked-, and mixed-type quantum-dot light-emitting diodes (QD-LEDs) for the next-generation smart white lighting have been analyzed and optimized by computational charge transport simulation and experiments.

In traditional power system state estimation application, the distribution of measurement noise is frequently assumed to be Gaussian. However, the distribution is sometimes unknown in practice and the above assumption may be wrong. In this paper, a totally distributed robust state estimation algorithm considering maximum exponential absolute value...

s Quantum dot light-emitting diodes (QD-LEDs) are considered as competitive candidate for next-generation displays or lightings. Recent advances in the synthesis of core/shell quantum dots (QDs) and tailoring procedures for achieving their high quantum yield have facilitated the emergence of high-performance QD-LEDs. Meanwhile, the charge-carrier d...

Beclomethasone dipropionate (1) is a widely used synthetic corticosteroid to treat asthma, allergic rhinitis, and dermatoses. This is so because of its anti-inflammatory, antipruritic, and anti-allergy properties. However, existing synthetic routes to this active pharmaceutical ingredient (API) contain low and inconsistent yielding steps, use of ob...

Progress toward the development of advanced supercapacitor technologies is closely associated with high-performance electrode materials. Carbon-based conductive additives modifying electrode material effectively improves the electronic conductivity and promotes the redox reaction. In this paper, we developed a highly effective binary conductive add...

Uncertainties in renewable energy sources and load demand have become a consequential issue which has led to a significant effect on the microgrid operation. In this paper, a novel cumulative relative regret decision-making strategy is proposed for the optimal energy management on a grid-connected multi-energy microgrid considering these uncertaint...

Distribution system state estimation (DSSE) plays a significant role for the system operation management and control. Due to the multiple uncertainties caused by the non-Gaussian measurement noise, inaccurate line parameters, stochastic power outputs of distributed generations (DG), and plug-in electric vehicles (EV) in distribution systems, the ex...

Propensity of a textile material to evaporate moisture from its surface, commonly referred to as the ‘moisture management’ ability, is an important characteristic that dictates the applicability of a given textile material in the activewear garment industry. Here, an infrared absorbing nanoparticle impregnated self-heating (IRANISH) fabric is devel...

Indoor photovoltaics have attracted considerable attention due to their great potential for powering low‐power electronics and photonic devices under ambient light. Bo Hou, Gehan A. J. Amaratunga and co‐authors (DOI: 10.1002/inf2.12180) provide an overview and prospect of the recent advances in various indoor photovoltaics. Indoor photovoltaics hav...

Indoor photovoltaics (IPVs) have attracted considerable interest for their potential to power small and portable electronics and photonic devices. The recent advancemes in circuit design and device optimizations has led to the power required to operate electronics for the internet of things (IoT), such as distributed sensors, remote actuators, and...

This paper investigates how to add a limited number of Phasor Measurement Units (PMUs) to the existing monitoring system so as to improve the estimation accuracy further. The existing methods are usually based on Gaussian noise assumption and the weighted least squares (WLS) estimator is taken into account. However, the Gaussian noise assumption is...

Synthesis of ultrathin heterostructures has received much attention in the recent past due to their unique physical and chemical properties. In this work, we report the synthesis of Fe2TiO5-TiO2 heterostructures using a simple hydrothermal technique employing natural ilmenite as the source. Hierarchically arranged nanostructures with interconnected...

Worldwide, urea remains the most widely used nitrogen fertilizer contributing to global food security. However, 70 80% of urea is lost during fertilization. Therefore, solutions for increasing its plant availability while reducing adverse effects to the environment caused by eutrophication and increase in greenhouse gases are of major importance in...

Synthesis of Levothyroxine sodium, the sodium salt of a synthetic levoisomer of thyroxine, revolutionized the management of hypothyroidism and related symptoms. However, the main synthetic route to this active pharmaceutical ingredient (API) is more than 70+ years old with low-yielding steps, obsolete reagents, and lacks experimental data on interm...

A unique zirconia nanomorphology possessing an enhanced photocatalytic efficiency was developed utilizing a convenient single-sol synthesis process which involved in-situ doping of zirconia by boron at the sol stage. The boron-doped zirconia exhibited a flake morphology as opposed to the spherical pure form and subsequent crystallographic investiga...

In order to advance the thin film silicon solar cell technology, it is desirable to replace the layers of doped thin film silicon or its alloys with alternative materials that can be deposited by simple physical vapor deposition (PVD) methods. Here, a dopant free a-Si:H solar cell design of Asahi U substrate | MoOx | a-Si:H | LiF | Al is investigat...

The use of carbon fiber-based composites in high-temperature environments has been hindered due to the inferior oxidation resistance of standard carbon fiber. Protective coatings comprised of refractory ceramics have served in enhancing the thermal endurance of carbon fiber significantly. Although zirconium and yttrium-based materials have been hig...

The distribution of measurement noise is commonly considered as an assumed Gaussian model in power systems but this assumption is not always true in reality. This paper introduces a distributed maximum-likelihood based state estimation approach for multi-area power systems using the Student’s t- distribution measurement noise model. The t-distribut...

Flexible capacitors are a promising power source for foldable and biological electronic devices. Although various materials and device structures have been explored, they are still limited by low energy densities and slow rate capabilities compared to their rigid counterparts. Here, asymmetric carbon nanohorns are proposed as an active material to...

There are numerous approximate color transforms reported in the literature that aim to reduce display power consumption by imperceptibly changing the color content of displayed images. To be practical, these techniques need to be content-aware in picking transformation parameters to preserve perceptual quality. This work presents a computationally-...

With the use of primaries which have increasingly narrow bandwidths in modern displays, observer metameric breakdown is becoming a significant factor. This can lead to discrepancies in the perceived color between different observers. If the spectral sensitivity of a user's eyes could be easily measured, next generation displays would be able to adj...

In order to advance the thin film silicon solar cell technology, it is desirable to replace the layers of doped thin film silicon or its alloys with alternative materials that can be deposited by simple physical vapor deposition (PVD) methods. Here, a dopant free a-Si:H solar cell design of Asahi U substrate | MoOx | a-Si:H | LiF | Al is investigat...

It is shown here that silicon (Si) based solar cells can be deposited by physical vapour deposition (PVD) methods only. These cells are called the PVD-Si cells. Their processing eliminates the deposition methods involving high temperature processing steps, and / or expensive, toxic and flammable gases used for processing conventional solar cells wi...

During the last three decades, studies of linamarin extracted from cassava have received increased attention due to the presence of high cyanogenic compounds in these extracts. The methods that are utilized to isolate linamarin are either tedious or use acidic conditions resulting in poor yields. In this study, a novel cryocooled method of extracti...

In power systems, optimal power flow (OPF) is a complex and constrained optimization problem in which quite often multiple and conflicting objectives are required to be optimized. The traditional way of dealing with multi-objective OPF (MOOPF) is the weighted sum method which converts the multi-objective OPF into a single-objective problem and prov...