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High‐power chemical lasers operating in high repetitive rate show a decrease of the output energy laser beam. In such lasers, the characteristic time which depends on the laser output is short in comparison with those related to the flow. Consequently, shock waves, acoustic waves and thermal perturbations, induced by the strong electric energy deposition and remaining in the laser cavity between two pulses, may explain the decrease of output energy of the laser beam. For a better understanding of the flowfields, a numerical approach is carried out using flux corrected transport algorithms (FCT methods) associated with a Riemann solver on the computational domain boundaries. Under two‐dimensional assumptions, the inviscid flow in the convergent‐divergent laser cavity is computed to describe the creation and propagation of the wave system and the hot gas column in both single and multidischarge operating modes. Distortions of the contact surfaces are put into evidence through the study of flowfield instabilities. Finally, the limitations of the two‐dimensional modelization become apparent. The numerical resolution is extended to a 3D case in order to take into account the optical direction. This allows to study the influence of shock waves travelling between optics and being generated by a side effect developing at the electrodes. These waves have an effect of long duration on the flowfield and lead to a high residual perturbation level.

A theoretical study is performed to investigate turbulent flow and heat transfer characteristics in a concentric annulus with a heated inner cylinder moving in the direction of flow (Couette flow). The two‐equation k‐ε model is employed to determine turbulent viscosity and kinetic energy. The Reynolds stress and turbulent heat flux are expressed by Boussinesq’s approximation. The governing boundary‐layer equations are discretized by means of a control volume finite‐difference technique and numerically solved using a marching procedure. Results are obtained for the time‐averaged streamwise velocity profile, turbulent kinetic energy profile, friction factor, and Nusselt number. These results agree well with experimental data in the existing literature. It is concluded from the study that the streamwise movement of the inner wall induces an attenuation in the turbulent kinetic energy, resulting in a reduction in the heat transfer performance and an increase in the velocity ratio of the moving inner cylinder to the fluid flow causes a substantial decrease in both the friction factor and the Nusselt number as well as a drastic reduction in the turbulent kinetic energy in the inner wall region.

This paper aims to show that by using air source heat pump (ASHP) water heater in the residential sector, the energy consumption from sanitary hot water production can be reduced by more than 50 per cent. Hence, this study quantitatively and qualitatively confirms that domestic ASHP water heater is a renewable and energy efficient device for sanitary hot water production.

Design and building of a data acquisition system comprises a data logger, power meters, flow meters, temperature sensors, ambient and relative humidity sensor and an electronic input pulse adapter to monitor the ASHP water heater performance. All the sensors are accommodated by the U30-NRC data logger. The temperature sensors are installed on the inlet pipe containing a flow meter and the outlet pipe of the ASHP unit, the vicinity of both evaporator and expel cold air. An additional temperature sensor and a flow meter that cater for hot water drawn off measurements are incorporated into the data acquisition system (DAS).

The result from a specific monitoring split type ASHP water heater gives an average daily coefficient of performance (COP) of 2.36 and the total electrical energy of 4.15 kWh, and volume of hot water drawn off was 273 L. These results were influenced by ambient temperature and relative humidity.

The cost involved in purchasing the entire sensors and data logger limits the number and categories of ASHP water heaters whose performance were going to be monitored. Pressure sensors were excluded in the data acquisition system.

The data acquisition system can easily be designed and the logger can also be easily programed. Hence, no high technical or computer skills are needed to install the DAS and to be able to read out the results.

Hence, the data acquisition system can be installed on the entire domestic Eskom roll out air source heat pump water heaters to effectively determine the coefficient of performance and demand reductions.

This DAS is the first of its kind to be built in South Africa to be used to determine the performance of an ASHP water heater with high accuracy and precision. DAS is also robust.

The purpose of this research is to study and investigate the flow control of 0.8 Mach jet using three tab configurations. The tabs with the slots will eventually lead to generation of vortices and thus enhances the mixing characteristics.

The jet flow control is achieved by the usage of three tabs, namely, Tab A, Tab B and Tab C that are placed at the exit plane of the convergent nozzle at 180 degrees apart. Three tabs with different slot profile are designed with the same constant blockage ratio of 7.3%. The tabs produce vortices of varying sizes that directly influence and modify the jet structure, thereby enhancing the efficiency in mass entrainment and mixing. The tabs are studied numerically first and then are compared with the results of the experiments.

The results are compared with that of the results of the uncontrolled jet. For Mach 0.8 jet, Tab C is found to reduce the core length and gives reduction of 90.23%, in comparison to Tab A and Tab B, which provides 84.1% and 87.79%, respectively. The results of numerical are then compared with the centerline results obtained via experiments. With the engagement of Tabs A, B and C, the jet structure is seen to have been modified at Mach 0.8 with Tab C performing better.

The tabs are a passive control device that can be practically enabled in the aircraft nozzles to control the flow and even suppress the noise emanated by the jet. Tabs can be effectively used for better thrust vector control and assist in jet noise suppression. Thus, this study on tabs and its uses are important and essential in aerospace technology.

This particular study on mechanical slotted tabs is innovatively carried out by designing the tabs in such a way that one such has not been designed before. The slots run through the adjacent sides of the tabs which is a novelty in itself, whereas perforations made only through the opposite sides of the tabs are studied by various researchers till now. The slots in the adjacent faces modify the flow physics in such a way that it enhances mixing by the creation of turbulence because of the interaction between the main stream and the secondary jet exactly at the core. So far, such slots and profiles are not investigated. By the usage of such tabs, the flow to mix faster is much closer to the core of the jet by creating mixed size vortices and thus has higher efficiency.

On its way to develop a smart grid in Indonesia, one key enabler in the early stage of implementation is advanced metering infrastructure (AMI). Thus, Perusahaan Listrik Negara (PLN), an electrical energy utility company owned by the government of the Republic of Indonesia as the only electricity utility company servicing customers from upstream to downstream in Indonesia, has started AMI program at some main cities. With AMI, real-time energy consumption profile, energy meter status and condition, and customer power quality can be acquired. Subsequently, these data collected by AMI can be used for further smart grid implementation by such IT systems and big data analysis. Instead of its function for smart grid backbone, AMI also significantly support smart energy on the city as a part of smart city initiatives. Nevertheless, its implementation requires more investment than the conventional metering system. This investment needs to be evaluated to define whether AMI is feasible and viable or not. This chapter is intended to observe the feasibility of AMI implementation in Indonesia using cost-benefit analysis (CBA). Two schemes were used as study objects, one scheme in which the communication infrastructure was managed by PLN itself, and the other one in which the communication infrastructure was managed by a third party. From the analysis, it appears that both schemes are proven to be feasible.

This paper aims to establish a more accurate model for lifetime estimation.

Finite element model simulation and experimental tests are used to enhance the lifetime prediction model of the solder joint.

A more precise model was found.

It is confirmed that the paper is original.

A QUARTER of a century ago, in September 1938, this journal published a review of diffuser behaviour by G. N. Patterson1 which, together with one of. its main information sources by Gibson,2 has formed the accepted guide to diffuser design. Patterson's paper was broad in scope and made clear reference to the effect of parameters which were not fully investigated until much later. It is the purpose of this paper to review experimental work, much of it being along the lines formulated by Patterson, and to indicate the improved analytical understanding of diffusers.

A transport model has been developed which is reasonably accurate, and has proven quite efficient for the two‐dimensional numerical simulation of submicron‐scale Si and GaAs devices. In this model an approximate form of the energy‐transport equation is developed; this equation is easily included in otherwise‐conventional device simulation codes, which then require only slightly more solution time than standard models using field‐dependent transport coefficients. Calculations for 0.25 micron gate length Si and GaAs MESFET's show that velocity overshoot effects can be very important, particularly in the latter material; predicted saturation currents in the GaAs devices are almost three times larger than those that would have been predicted using conventional transport models. The model described, and its application in simulation programs, should find use in the design of submicron‐scale devices to properly take advantage of overshoot phenomena.

Sustainability is an accepted measure of business performance, with reductions in energy demand a commonly practised sustainability initiative by multinational corporations (MNCs). Traditional energy models have limited scope when applied to the entire MNC as the models exhibit high data and time intensity, high technical proficiency, specificity of application and omission of non-manufacturing activities. The purpose of this paper is to propose a process centric energy model (PCEM), which adopts a novel approach of applying business processes for business energy assessment and optimisation. Business processes are a fundamental requirement of MNCs across all sectors. The defining features of the proposed model are genericity, reproducibility, minimum user input data, reduced modelling time and energy evaluation of non-manufacturing activities. The approach forwards the adoption of Industry 4.0, a subset of which focuses on business process automation or part thereof.

A quantitative approach is applied in development of the PCEM. The methodology is demonstrated by application to the procure to pay and electroplating business processes.

The PCEM quantifies and optimises the business energy demand and associated carbon dioxide emissions of the procure to pay and electroplating business processes, validating the application of business processes. The application demonstrates minimum user inputs as only equipment operational parameters are required and minimum modelling time as business process models and optimisation options are pre-defined requiring only user modification. As MNCs have common business processes across multiple sites, once a business process energy demand is quantified, its inputs are applied as the default in the proceeding sites, only requiring updating. The model has no specialist skills requirement enabling business wide use and eliminating costs associated with training and expert’s services. The business processes applied in the evaluation are developed by the researchers and are not as comprehensive as those in actual MNCs, but is sufficiently detailed to accurately calculate an MNC energy demand. The model databases are not exhaustive of all resources found in MNCs.

This paper provides a new approach to MNC business energy assessment and optimisation. The model can be applied to MNEs across all sectors. The model allows the integration of manufacturing and non-manufacturing activities, as it occurs in practice, providing holistic business energy assessment and optimisation. The model analyses the impacts of the adoption of Industry 4.0 technologies on business energy demand, CO₂ emission and personnel hours.

The purpose of this paper is the evaluation of the influence of pole and teeth shapes on the behaviour of a linear switched reluctance actuator (LSRA). The study was carried out through the application of a finite element static analysis and the application of a new method for dynamic analysis. Those studies are thereafter evaluated with experimentations.

The paper characterizes the performance of an LSRA for different polar geometries. A finite element tool is used at an early research stage. Results are then used to build a dynamic numerical model. Obtained data allow the construction of a laboratory prototype.

Polar shape has great influence in actuator behaviour. Different geometrical polar configurations are evaluated and their influence is observed. The obtained data allow attraction force minimization with minimal penalty in the thrust force. A numerical dynamic model is used to evaluate actuator movement with different polar shapes, without taking into consideration the influence of magnetic losses.

This paper allows the knowledge of each pole shape configuration to be adopted according to the actuator application and desired performance.

This paper presents the effect of the different pole shapes on the behaviour of static and dynamic characteristics of the LSRA. It is shown that the use of non‐traditionally pole shapes, round or wedge, leads to a small penalty in thrust force and a considerable attraction force minimization. The benefit in actuator effects concerning mechanical structure and performance is evident.