Towards Sustainable Municipal Solid Waste Management in Malaysia

This work is part of the SYNERGORS project (“A Systems Approach to Synergistic Utilisation of Secondary Organic Streams”) funded by the UKRI Natural Environment Research Council (NE/R012938/1) through the UKRI/NERC Industrial Innovation Fellowship Programme (2018-2021). This project was led by Dr Kok Siew Ng at University of Oxford. Website: https://eng.ox.ac.uk/synergorsProject summary report: https://eng.ox.ac.uk/media/10670/synergors-final-report.pdfEXECUTIVE SUMMARY: The increasing amount of municipal solid waste (MSW) generation and the lack of strategic improvements on solid waste management in Malaysia require urgently the attention of the government and the public.It has been estimated that 1.17 kg/capita/day of MSW is generated in Malaysia, 65% of which is household solid waste that has doubled over the past 20 years due to population growth and urbanisation. Without a sufficient waste treatment and recycling infrastructure in place, most of the MSW is destined to continue to be landfilled. Not only it can cause pollution and health hazards, MSW is also one of the major sources of global methane emissions accounting for 11%. As methane is the second largest contributor of global greenhouse gas emissions after carbon dioxide, it is critical that Malaysia develops systemic sound solid waste management as part of its climate actions guided by the Paris agreement. Also, by treating waste as resource, the recent shift in the government strategy to move towards the circular economy should be aligned with SDG 12 targets (Responsible Consumption and Production). Although the quantity of recyclable waste collected tripled between 2018 and 2021, the officially reported recycling rate of 31.5% in 2021 remains questionable as the recycling infrastructure in Malaysia is not yet well established. This points to the significant efforts Malaysia needs to make to move towards a sustainable waste management regime, and to achieve its ambition for reaching a recycling target of 40% by 2025. Malaysia started implementing a plan for moving towards sustainable waste management in the early 1990s. However, the recycling programmes were not well received by the public at that time, and it was only in 2001, that policy goals for sustainable waste management have been included in the regulatory landscape through the 8th Malaysia Plan (2001-2005). In 2005, the National Strategic Plan for Solid Waste Management was developed to guide solid waste policy planning and resource allocation. Two years after, the Solid Waste and Public Cleansing Management Act 2007 (Act 672) was created that came into enforcement in September 2011 in six out of the thirteen states (Perlis, Kedah, Pahang, Negeri Sembilan, Melaka, Johor) and two out of the three federal territories (i.e. Kuala Lumpur and Putrajaya). This partial adoption of the Act has created inconsistency in waste management and planning as well as incomplete waste data gathering. This,has led to ineffective waste management practices, that, in turn, resulted in long-term environmental, economic and social consequences. Even though sustainable waste management goals continue to be included in the recent 12th Malaysia Plan (2021-2025), the lack of public awareness on the importance of source separation of waste and recycling prevents progress in this field. The infrastructure for waste collection and treatment is also insufficient to serve the needs. All these factors have created significant barriers for Malaysia to realise sustainable waste management.UK Natural Environment Research Council (NE/R012938/1

Evaluation of two interaction techniques for visualization of dynamic graphs

Several techniques for visualization of dynamic graphs are based on different spatial arrangements of a temporal sequence of node-link diagrams. Many studies in the literature have investigated the importance of maintaining the user's mental map across this temporal sequence, but usually each layout is considered as a static graph drawing and the effect of user interaction is disregarded. We conducted a task-based controlled experiment to assess the effectiveness of two basic interaction techniques: the adjustment of the layout stability and the highlighting of adjacent nodes and edges. We found that generally both interaction techniques increase accuracy, sometimes at the cost of longer completion times, and that the highlighting outclasses the stability adjustment for many tasks except the most complex ones.Comment: Appears in the Proceedings of the 24th International Symposium on Graph Drawing and Network Visualization (GD 2016

Computational Fluid Dynamics Simulation of Gas-Solid Hydrodynamics in a Bubbling Fluidized-Bed Reactor: Effects of Air Distributor, Viscous and Drag Models

In this work, we employed a computational fluid dynamics (CFD)-based model with a Eulerian multiphase approach to simulate the fluidization hydrodynamics in biomass gasification processes. Air was used as the gasifying/fluidizing agent and entered the gasifier at the bottom which subsequently fluidized the solid particles inside the reactor column. The momentum exchange related to the gas-phase was simulated by considering various viscous models (i.e., laminar and turbulence models of the re-normalisation group (RNG), k-ε and k-ω). The pressure drop gradient obtained by employing each viscous model was plotted for different superficial velocities and compared with the experimental data for validation. The turbulent model of RNG k-Ɛ was found to best represent the actual process. We also studied the effect of air distributor plates with different pore diameters (2, 3 and 5 mm) on the momentum of the fluidizing fluid. The plate with 3-mm pores showed larger turbulent viscosities above the surface. The effects of drag models (Syamlal–O’Brien, Gidaspow and energy minimum multi-scale method (EMMS) on the bed’s pressure drop as well as on the volume fractions of the solid particles were investigated. The Syamlal–O’Brien model was found to forecast bed pressure drops most consistently, with the pressure drops recorded throughout the experimental process. The formation of bubbles and their motion along the gasifier height in the presence of the turbulent flow was seen to follow a different pattern from with the laminar flow.Ministry of Higher Education (MOHE) Malaysia; Engineering and Physical Sciences Research Counci

Insulin resistance, lipotoxicity, type 2 diabetes and atherosclerosis: the missing links. The Claude Bernard Lecture 2009

Insulin resistance is a hallmark of type 2 diabetes mellitus and is associated with a metabolic and cardiovascular cluster of disorders (dyslipidaemia, hypertension, obesity [especially visceral], glucose intolerance, endothelial dysfunction), each of which is an independent risk factor for cardiovascular disease (CVD). Multiple prospective studies have documented an association between insulin resistance and accelerated CVD in patients with type 2 diabetes, as well as in non-diabetic individuals. The molecular causes of insulin resistance, i.e. impaired insulin signalling through the phosphoinositol-3 kinase pathway with intact signalling through the mitogen-activated protein kinase pathway, are responsible for the impairment in insulin-stimulated glucose metabolism and contribute to the accelerated rate of CVD in type 2 diabetes patients. The current epidemic of diabetes is being driven by the obesity epidemic, which represents a state of tissue fat overload. Accumulation of toxic lipid metabolites (fatty acyl CoA, diacylglycerol, ceramide) in muscle, liver, adipocytes, beta cells and arterial tissues contributes to insulin resistance, beta cell dysfunction and accelerated atherosclerosis, respectively, in type 2 diabetes. Treatment with thiazolidinediones mobilises fat out of tissues, leading to enhanced insulin sensitivity, improved beta cell function and decreased atherogenesis. Insulin resistance and lipotoxicity represent the missing links (beyond the classical cardiovascular risk factors) that help explain the accelerated rate of CVD in type 2 diabetic patients

Measurement and interpretation of same-sign W boson pair production in association with two jets in pp collisions at s = 13 TeV with the ATLAS detector

This paper presents the measurement of fducial and diferential cross sections for both the inclusive and electroweak production of a same-sign W-boson pair in association with two jets (W±W±jj) using 139 fb−1 of proton-proton collision data recorded at a centre-of-mass energy of √s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity diference. The measured fducial cross sections for electroweak and inclusive W±W±jj production are 2.92 ± 0.22 (stat.) ± 0.19 (syst.)fb and 3.38±0.22 (stat.)±0.19 (syst.)fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confdence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H±± that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H±± mass near 450 GeV, with a global signifcance of 2.5 standard deviations

Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at s = 13 TeV with the ATLAS detector

A combination of searches for new heavy spin-1 resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at = 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb, , and tb) or third-generation leptons (τν and ττ) are included in this kind of combination for the first time. A simplified model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confidence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion