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Rapid tooling (RT) integrated with additive manufacturing technologies have been implemented in various sectors of the RT industry in recent years with various kinds of prototype applications, especially in the development of new products. The purpose of this study is to analyze the current application trends of RT techniques in producing hybrid mold inserts.

The direct and indirect RT techniques discussed in this paper are aimed at developing a hybrid mold insert using metal epoxy composite (MEC) in increasing the speed of tooling development and performance. An extensive review of the suitable development approach of hybrid mold inserts, material preparation and filler effect on physical and mechanical properties has been conducted.

Latest research studies indicate that it is possible to develop a hybrid material through the combination of different shapes/sizes of filler particles and it is expected to improve the compressive strength, thermal conductivity and consequently increasing the hybrid mold performance (cooling time and a number of molding cycles).

The number of research studies on RT for hybrid mold inserts is still lacking as compared to research studies on conventional manufacturing technology. One of the significant limitations is on the ways to improve physical and mechanical properties due to the limited type, size and shape of materials that are currently available.

This review presents the related information and highlights the current gaps related to this field of study. In addition, it appraises the new formulation of MEC materials for the hybrid mold inserts in injection molding application and RT for non-metal products.

Over past decades, the fossil fuel reserves in the world have been decreasing at an alarming rate and a lack of crude oil is expected in the early decades of this century. Also, the eco-neutral pollutants such as carbon monoxide (CO), oxides of nitrigen (NOx) and unburnt hydrocarbons (UHC) are also increasing. This calls for innovative research in non-conventional fuels to replace fossil fuels. Hydrogen is one such fuel which has an exceptional combustion property and appears to be proving itself as the best transportation fuel of the future. On the other hand, compressed natural gas(CNG) has already been credited as a remarkable fuel for its better emission characteristics and has been implemented as a transportation fuel in metros. Therefore, the use of hydrogen blended with natural gas seems to be a viable alternative to pure fossil fuels because of the expected reduction of the total pollutants and increase of efficiency. This paper aims to investigate this issue.

In the present experimental investigation, 10 and 20 per cent of hydrogen–CNG mixture(HCNG) by mass of fuel is inducted into the combustion chamber in conjunction with air in HCNG–diesel dual fuel mode. The variation in injection opening pressure is assessed to optimize the performance and emission characteristics.

Experiments were conducted at three different injection opening pressures, i.e. 200, 220 and 240 bar, at full-load condition and the performance characteristics were calculated. The effect of injection operating pressure(IOP) on emissions were measured and compared with pure diesel mode.

Brake thermal efficiency (BTE) was increased by 1.2 per cent at 220 bar. Minimum BSFC of 0.2302 kg/kWh, 0.2114 kg/kWh was noticed for 220 bar with a changing ratio of 20 per cent of HCNG. It was noticed that CO and UHC decreased with variation in IOP and HCNG content in the blend. However, there was an increase in NOx emissions.

Homogeneous charge compression ignition (HCCI) engine is an advanced combustion method to use alternate fuel with higher fuel economy and, reduce NOX and soot emissions. This paper aims to investigate the influence of ethanol fraction (ethanol plus gasoline) on dual fuel HCCI engine performance.

In this study, the existing CI engine is modified into dual fuel HCCI engine by attaching the carburetor to the inlet manifold for the supply of ethanol blend (E40/E60/E80/E100). The mixture of ethanol blend and the air is ignited by diesel through a fuel injector into the combustion chamber at the end of the compression stroke. The experiments are conducted for high load conditions on the engine i.e. 2.8 kW and 3.5 kW maximum output power for 1,500 constant rpm.

It is noticed from the experimental results that, with an increase of ethanol in the blends, ignition delay (ID) increases and the start of combustion is retarded. It is noticed that E100 shows the highest ID and low in-cylinder pressure; however, E40 shows the lowest ID compared to higher fractions of ethanol blends. An increase in ethanol proportion reduces NOX and smoke opacity but, HC and CO emissions increase compared to pure diesel mode engine. E100 plus diesel dual-fuel HCCI engine shows the highest brake thermal efficiency compared to remaining ethanol blends and baseline diesel engine.

This experimental study concluded that E100 plus diesel and E80 plus diesel gave optimum dual fuel HCCI engine performance for 2.8 kW and 3.5 kW rated power, respectively.

With the threat of climate change increasing, carbon sequestration could be expected to play a significant role in alleviating this problem. Unfortunately, the technology is not well understood and good literature overviews of the options in carbon sequestration are lacking. Hence, policy and research priorities are made without full understanding of the state of scientific knowledge, impacts, and policy trade‐offs. This paper contributes to the literature, providing a basic picture of the technological options for futurists and policy advisors to begin to address this need.

The purpose this experimentation is to study the combustion characteristics of compression ignition engine fuelled with mineral diesel. The reason behind the numerical simulation is to validate the experimental results of the combustion characteristics.

The numerical analysis was carried out in this study using MATLAB Simulink, and the zero dimensional combustion model was applied to predict the combustion parameters such as in cylinder pressure, pressure rise rate and rate of heat release.

Incorporating the dynamic combustion duration with respect to variable engine load in the zero dimensional combustion model using MATLAB Simulink reduced the variation of experimental and numerical outputs between 5.5 and 6 per cent in this analysis.

Validation of the experimental analysis is very limited. Investigations were performed using zero dimensional combustion model, which is the very appropriate for analysing the combustion characteristics.

Existing studies assumed that the combustion duration period as invariant in their numerical analysis, but with the real time scenario occurring in CI engine, that is not the case. In this analysis, mass fraction burnt considering the dynamic combustion duration was incorporated in the heat transfer model to reduce the error variation between experimental and numerical studies.

To the Editor. DEAR SIR, In the June issue of AIRCRAFT ENGINEERING, Mr V. D. Naylor rightly asserts that, according to one‐dimensional theory, the velocity at the throat of a Laval nozzle is the local sonic velocity, whether friction is present or not. However his proof rests on an expansion law pvn=constant, when n≠y, and the throat velocity which he obtains differs according to the value of n. Both the assumption and the conclusion are false. The confusion which has existed on this point is, therefore, deepened.

COVID-19 is a global pandemic that was unprecedented in human history. The scale of infection was unusual with most countries succumbing to this disease. Various mitigation plans were introduced by governments around the world to contain the spread of the virus. The Southeast Asian region is not spared from the harmful effects of COVID-19. Most Southeast Asian countries responded swiftly to COVID-19 by introducing stringent policies such as contact tracing, mandatory quarantine, restriction of movements, cancellation of public events, health screenings, and border closures early on to tackle the rapid spread of the virus. The adoption of technology for contact tracing such as MySejahtera (Malaysia), TraceTogether (Singapore), PeduliLindungi (Indonesia), Mor Chana (Thailand), and Stay Safe (Philippines) shows the rapid response from the governments to contain the spread of COVID-19. The variation in the degree of success stories at different timelines in managing COVID-19 in the region indicates that COVID-19 management requires short and long-term planning, especially in the public health policy. In the case of Malaysia, the first phase of movement control order (MCO, 18–31 March 2020) took place on the background of political turmoil. The newly formed government under the leadership of Muhyiddin Yasin announced the first phase of lockdown in Malaysia to control the rising number of COVID-19 cases. The lockdowns then evolved into different forms at different phases of implementation until it was announced on 8 March 2022 that the country is transitioning to the endemic phase on 1 April 2022. This study shows that the respondents to our survey during the first phase of MCO are highly aware of the government’s initiatives to manage COVID-19 and the Malaysian public has a high level of trust and confidence in the government’s initiatives. The stringent measures taken by the government in the first wave of COVID-19 were seen as a necessity and it provided legitimacy to the government despite being the first unelected government in Malaysian history.

The global economy is plagued by an unprecedented shock that has devastated economic growth under the coronavirus pandemic. The prolonged movement control orders, social distancing, and lockdowns have triggered the global economic downturn, disrupted the demand and supply chains, reduced the pool of workforce, and caused many jobs loss. This paper aims to analyze the global economic cost of the coronavirus pandemic, and its current and future implications.

Based on contingency theory, this paper provides an in-depth analysis of the current situation on the global economic cost of the COVID-19 outbreak and gives insights from an organizational perspective.

This paper found that the world has witnessed far-ranging economic consequences due to the coronavirus pandemic in four aspects: (i) decline in personal consumption; (ii) decline in the investments and stock prices in capital market; (iii) decline in government spending in developmental projects and increase in new borrowing; and (iv) decline of exports of goods to international markets.

The novelty lies in investigating the effects of the COVID-19 pandemic on micro and macroeconomic levels — the components of GDP, consumer behavior, business investments, government spending, and global exports. The paper suggests the need for urgent actions by the world leaders to oversee, anticipate, and manage the risks and cushion the economic consequences. It concludes that the flexibility and adaptability of leaders, effectiveness, workforce protection, efficient use of modern technology, including automation and artificial intelligence, would enhance the resilience of supply chains which will support organizations to sustain in this critical time.

The purpose of this paper is to investigate power performance, economy and hydrocarbons (HC)/carbon monoxide (CO) emissions of diesel fuel on a two-stoke direct injection (DI) spark ignition (SI) engine.

Experimental study was carried out on a two-stroke SI diesel-fuelled engine with air-assisted direct injection, whose power performance and HC/CO emissions characteristics under low-load conditions were analysed according to the effects of ignition energy, ignition advance angle (IAA), injection timing angle and excess-air-ratio.

The results indicate that, for the throttle position of 10%, a large IAA with adequate ignition energy effectively increases the power and decrease the HC emission. The optimal injection timing angle for power and fuel consumption is 60° crank angle (CA) before top dead centre (BTDC). Lean mixture improves the power performance with the HC/CO emissions greatly reduced. At the throttle position of 20%, the optimal IAA is 30°CA BTDC. The adequate ignition energy slightly improves the power output and greatly decreases HC/CO emissions. Advancing the injection timing improves the power and fuel consumption but should not exceed the exhaust port closing timing in case of scavenging losses. Burning stoichiometric mixture achieves maximum power, whereas burning lean mixture obviously reduces the fuel consumption and the HC/CO emissions.

Gasoline has a low flash point, a high-saturated vapour pressure and relatively high volatility, and it is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. The authors adopt a low volatility diesel fuel for all vehicles and equipment to minimise the number of different devices using various fuels and improve the potential military application safety.

Under low-load conditions, the two stroke port-injected SI engine performance of burning heavy fuels including diesel or kerosene was shown to be worse than those of gasoline. The authors have tried to use the DI method to improve the performance of the diesel-fuelled engine in starting and low-load conditions.