A novel criterion for quantifying the resilience of power systems supplying data centres is formulated to measure the system's ability to sustain functionality even during an outage. By comparative analysis of two alternative data centre power systems covering apparatus of electrical power supply and environmental control, it is shown that reliability and availability alone are insufficient as metrics to gauge different designs. The gap is bridged by the proposed resilience analysis to further evaluate situations of single and double outages. As a complement to the indicators of single point of failure and double point of failure, respectively, and security criteria, the novel metrics of a single point of reduced availability and double point of reduced availability are proposed. These criteria identify those single subsystems or subsystem pairs causing system availability to drop below requested levels in periods when they are out of service. The metrics so offer information on the overall system's availability during times of maintenance and failures. Thanks to this understanding, it is shown that a guided reduction of the number of subsystems considering their relative importance can lead to designs offering desirable trade-offs in terms of complexity, reliability, availability, and resilience.

A novel compact design of a circularly polarised corner-slotted microstrip antenna for satellite and synthetic aperture radar (SAR) applications is presented. A single-feed is used to excite a single-square patch with two L-shaped slots added at the upper right corner and at the opposite lower left corner (or at the other two corners) to achieve circular polarisation (CP) radiation. The proposed antenna has a simple shape, straightforward fabrication, and low cost. The impedance bandwidth (10 dB return loss) is ∼600 MHz at 8.1 GHz. An axial ratio bandwidth of 170 MHz is realised. The importance of the axial ratio 3 dB bandwidth is emphasised. In addition, an analysis for the direction of rotation of the CP is given. The experimental results have a reasonable agreement with the simulation.

Common practice in transmission and distribution (T&D) systems analysis has been to treat them independently by decoupling those at the point of common coupling (PCC). With the large amount of distributed energy resources (DER) being added in distribution networks, the interactions between T&D systems at PCC produce unacceptable errors. This study discusses an alternate approach for the combined T&D systems analysis using co-simulation technique. The proposed framework couples the analysis of the two systems by iteratively exchanging the power flow variables at the PCC. The approach is implemented for an IEEE 9-bus transmission test system coupled with the IEEE 13-bus distribution test system and the analysis is validated against an equivalent stand-alone combined T&D system model.

The dual active full bridge (DAFB) is one of the promising isolated DC/DC converter topologies that will play a significant role in the future of electric vehicle (EV) integration in smart grids (SGs). This is due to its inherent soft switching and control simplicity. Therefore, this study presents first the latest developments related to the design of DAFB converter in EV charging technology. It provides a brief discussion of the crucial recommendations regarding the reliability, efficiency, system configuration, EV charger control scheme, battery lifetime, and system materials. Then, it presents a step-by-step modelling approach for a non-ideal DAFB for the purpose of designing its controller. In addition, the model provided by this study includes all non-idealities due to the high-frequency (HF) transformer, semiconductor switches, passive components, and digital system delays. Eventually, the proposed system design and analysis was validated by implementing a 6.1 kW prototype on Simulink and Typhoon-HIL real-time simulator.

The rise of civil aviation cargo industry has greatly increased the speed of global logistics, and the relatively high cost and limited loading space of civil aviation aircraft determines that civil aviation aircraft companies need to optimise the cargo assembly scheme to achieve the high loading rate under the limited cost. This study briefly introduced the mathematical model and genetic algorithm of civil aviation cargo aircraft assembly and improved the fixed crossover and mutation probabilities of genetic algorithm to adaptive crossover and mutation probabilities. Then two algorithms were simulated and analysed in MATLAB software. The results showed that the improved genetic algorithm converged faster in the optimisation of cargo aircraft transportation assembly model and had higher adaptability after stabilisation. In terms of load and volume utilisation ratio of cargo hold, the assembly scheme optimised by the improved genetic algorithm has higher load and volume utilisation ratio. In conclusion, the improved genetic algorithm is suitable for the optimisation of the transport assembly model of civil aviation cargo aircraft.

With the continuous development of radar terminal guidance technology, the evaluation of the performance of a radar seeker has become a very necessary and important system subject. Rationally allocating the index weight has always been an important spot in the research of performance evaluation. For this problem, a new method based on importance level to allocate the index weights is proposed, which can both reflect the subjective opinion of an expert and the objective facts. Second, rather than evaluate radar seeker performance in simulation test and outfield experiment, respectively, information fusion is applied to evaluate the radar performance instead of serial-phased scheme which takes advantage of both infield simulated and outfield measured data. Furthermore, a model was proposed to calculate the weights of each information element in the information-fusion stage. Considering that the performance evaluation of a radar seeker involves many experimental stages, information fusion which can make full use of the multi-source test information can help to obtain more accurate and reliable evaluation conclusion. Both the theoretical analysis and experimental results prove the effectiveness and efficiency of the proposed method.

Parasitic capacitances in high frequency have a significant role in examining the inductor-capacitor tank oscillators (LC oscillators) output signal quality. Here, the authors proposed a new idea for Ka-band satellite receiver oscillator, which considers these parasitic elements, in order to maintain a specific precise frequency where there is no need for a broadband frequency range. By using tuned parasitic elements in differential LC oscillator to resonate the circuit's common mode at twice the oscillation frequency, a better phase noise performance and higher oscillator FOM can be achieved. The developed methodology is employed to design and fabricate an oscillator in 0.25 µm AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors process for 19.25 GHz oscillations.

Pixelated optical communication systems transmit data using a series of encoded pixelated images. The decoding of these pixelated images is important for reliable data communication. This study proposes a novel intensity gradient-based edge detection (IGED) method for the received pixelated images. In the first stage of the proposed edge detection algorithm, the intensity difference of neighbouring pixels is calculated in the horizontal or vertical direction depending on the presence of a horizontal or vertical edge. In the second stage, the false edge pixels whose intensity values are less than the threshold are removed. Next, slopes are calculated between the consecutive edge pixels and the appropriate lines are found considering the slopes that have almost the same value. The new IGED method performs edge detection without requiring any anchor pixel blocks. This study also provides a description of a misalignment correction algorithm suitable for pixelated images. Next, the effectiveness of the proposed IGED method is tested through an experimental demonstration. It is shown that the IGED method can properly detect the edges even for pixelated images affected by rotational misalignment. For a given transmitter resolution, the proposed method provides better data rates than the existing methods.

A sensitivity analysis method for the wind power capacity of integrated energy systems based on unified optimal power flow is proposed, aiming at the large-scale grid-connected wind power problem of integrated energy systems with multiple energy sources and strong coupling characteristics. Based on the unified optimal power flow model of integrated energy system with power system, heat system and gas system, this study establishes the sensitivity analysis method of integrated energy system operation state. Based on the sensitivity matrix, the influence of wind power consumption capability by capacity of energy coupling unit on wind power consumption is analysed. The results of the example show that the proposed method can provide auxiliary information for the safe and stable operation of the integrated energy system, and effectively improve the wind power acceptance level.

It is an important subject to mine valuable knowledge from complex and massive data in the era of big data. Rough set theory is a new mathematical tool for dealing with uncertain and inaccurate data, decision-theoretic rough set model (DTRS), as an extension of classical rough set model, is used to analyze decision information systems and multi-granulation decision-theoretic rough set model (MG-DTRS) can analyze and process target concepts from different angles and levels. However, the classical DTRS model exists some limitations in dealing numerical or hybrid-valued data. Considering the different influence of numerical features and symbolic features on decision-making, the paper proposes an incomplete neighborhood multi-granulation decision-theoretic rough set model in hybrid-valued decision system through integrating MG-DTRS with neighbourhood rough sets, and two types of neighborhood multi-granulation decision-theoretic set models are emphatically analysed. Furthermore, taking pessimistic and optimistic neighborhood multi-granulation decision-theoretic rough sets as examples, the implementation algorithms and related properties of the two type of models are studied. Finally, the relationship between the proposed model and other models is analyzed through formula derivation. The model proposed in this paper can effectively solve the decision-making problem of hybrid-valued incomplete information system through multi-angle and multi-level analysis.

This study studies, using experimentally verified finite element (FE) analysis, various performance measures of the brushless doubly fed induction generator (BDFIG) when magnetic wedges are used for closing stator open slots. The BDFIG is an attractive generator solution for offshore wind power and can replace doubly fed slip-ring induction generators. It is shown in this study that the use of magnetic wedges, commonly used in large induction machines, reduces the stator windings magnetising currents in a BDFIG, reflected in the values of magnetising inductances. They also increase the leakage flux in the stator slots, leading to a larger series inductance in the equivalent circuit. The series inductance significantly affects the BDFIG performance as well as the rating of its converter. The effects of magnetic wedges on BDFIG air-gap flux, synchronous torque, and stator tooth top saturation is also investigated. Two-dimensional FE analysis of an experimental 250 kW BDFIG is used in this study, verified by experimental measurements.

This work investigates the potential for off-the-shelf hardware to be used as a very low-cost replacement to the expensive missile test telemetry currently used by military equipment suppliers to develop flight guidance systems. Missile tests are essential to create highly accurate simulation models of the missile flight controls to ensure accuracy of live missile fire and fully controlled stability throughout the flight to ensure the missile only strikes intended targets. Since test missiles are expensive one-shot devices the telemetry gathered must be transmitted robustly over the full flight. Development of bespoke telemetry units is expensive; thus the potential for using off-the-shelf components and sub-assemblies to provide telemetry based on the Wi-Fi communications standard is investigated. Over the course of missile development, this would create remarkable financial savings. This work details the design, development, and testing of a Wi-Fi missile telemetry system with the solution being evaluated against required performance requirements. Received signal strength and packet error rate, indicators of communication link quality, were investigated for increasing distance and for multi-frequency vibration. These tests replicate in-flight parameters for the transmitter's operation. Conclusions are presented along with recommendations for future development work.