Origins of one dimensional instability in stationary shock and slowly moving shock

Shock instabilities in the numerical sense include the carbuncle phenomenon and the slowly moving shocks. The carbuncle phenomenon is a term referred to the protruding formation at the stagnation region in addition to the continuous bow shock when simulating a high-speed flow over a blunt body. Most schemes formulated to cure this problem only focus on the dissipation methods without properly indulged into the real cause, which could also be the root problem for the slowly moving shock. Therefore, this paper attempted to find the source of the problem by firstly analyzing the governing equations starting from 1D case. After using perturbation mechanism on the conservative variables, several factors were found and one of them is caused by perturbation in density. Then, a dissipation was added to the RHS (right-hand side) of the continuity equation to remove the perturbation. This artificial dissipation has shown stable solutions for both stationay and slowly moving shock problems

Bivariate causality between exchange rates and stock prices in Malaysia

The main purpose of this paper is to examine the relationship between stock prices and exchange rates in Malaysia. This research considers high-frequency data of USD-MYR exchange rates and Kuala Lumpur Composite Index (KLSE) from July 22, 2005 to March 23, 2007, which is the period when the MYR was unpegged. The Johansen cointegration method suggests that there is no long-run equilibrium relationship between these two financial variables. Both Engle Granger and Toda-Yamamoto causality tests find that there is uni-directional causality running from stock prices to exchange rates

Long Memory and Parity Reversion in Real Exchange Rate

This paper examines the post Bretton Woods experience of the Malaysian Ringgit. In this period, Malaysia moved from a managed to a floating exchange rate environment.We examine persistence in real exchange rates by estimating fractionally integrated ARIMA models and find evidence of long memory, which induces persistence though this long memory need not be associated with a unit root. The results show that three out of four exchange rates being examined display mean reversion. The long memory process re-establishes the Purchasing Power Parity as a meaningful concept of long-run equilibrium relation between the exchange rate and relative prices

Agriculture: Innovations in Vertical Cultivation Systems for Community Development

This paper explores potential barriers to the adoption of soil-less, small-scale hydroponic systems operated through digital technology within gardening communities and related projects. It investigates whether these communities view a technology-driven approach to food cultivation as limiting. The backdrop of the COVID-19 pandemic highlights interconnected challenges spanning food security, climate change, and economic turmoil. Disruptions in global supply chains and economic activities resulting from the pandemic have precipitated an economic crisis, income disparities, and increased food insecurity. Agricultural disruptions have exacerbated food security issues, while climate change-induced extreme weather events further jeopardize food systems. This economic crisis impedes effective climate change mitigation and adaptation. A holistic approach is crucial, integrating sustainable agriculture, resilient food systems, and climate change strategies. Collaboration among governments, researchers, and communities is vital for enduring food security and sustainable economies. The Hydroponic Verticulture System (HVS), a modern urban agricultural technology, offers a practical solution that fosters urban farming, ensures food quality, and supports community engagement. A full tank of water or mixed organic material of 13.5 Liter with 5rm speed provided sufficient watering for effective nourishment and hydration throughout the vertical system. Furthermore, HVS contributes to climate change mitigation by reducing CO2 and increasing O2 levels through smart urban farming practices, aligning with environmental sustainability goals

Monitoring the Construction Industry towards a Construction Revolution 4.0

The key concept of the Industrial Revolution IR 4.0 has been conceptualized as the new wave of digitalization, robotization, and broader usage of information and communication technology. However, the construction industry is complicated, which has led to its slow industrial evolution. The construction industry still follows traditional labor-intensive industry practices, with high energy consumption, environmental pollution, and low productivity in project delivery. Moreover, the recent cataclysmic COVID 19 pandemic has opened the vision of the construction industry towards IR 4.0 due to the human movement restriction. This paper aims to investigate the adoption of indispensable monitoring technology in the construction industry as effective visual communication of data towards the IR 4.0. This research closes the gap and gives an intensive literature investigation to acquire insights into Construction 4.0 and a case study to showcase the developed monitoring dashboard. Adoption of IR 4.0 technologies will achieve sustainable construction development, lower costs and fast construction with the highest quality. The critical literature review of previous studies with content analysis to demonstrate the recent research in this area. The monitoring dashboard brings the construction performance assessment data to real life and provides key performance indicators required for construction management and support decisions

Low-dimensional galerkin approximations of nonlinear delay differential equations

This article revisits the approximation problem of systems of nonlinear delay differential equations (DDEs) by a set of ordinary differential equations (ODEs). We work in Hilbert spaces endowed with a natural inner product including a point mass, and introduce polynomials orthogonal with respect to such an inner product that live in the domain of the linear operator associated with the underlying DDE. These polynomials are then used to design a general Galerkin scheme for which we derive rigorous convergence results and show that it can be numerically implemented via simple analytic formulas. The scheme so obtained is applied to three nonlinear DDEs, two autonomous and one forced: (i) a simple DDE with distributed delays whose solutions recall Brownian motion; (ii) a DDE with a discrete delay that exhibits bimodal and chaotic dynamics; and (iii) a periodically forced DDE with two discrete delays arising in climate dynamics. In all three cases, the Galerkin scheme introduced in this article provides a good approximation by low-dimensional ODE systems of the DDE's strange attractor, as well as of the statistical features that characterize its nonlinear dynamics.Comment: 6 figures and 1 tabl