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A novel 1 × 4 phased array elliptical inverted T-shaped slotted sectored patch antenna with defected ground structure (DGS), resonate at proposed ultra-wide tetra band at 28, 43, 51, and 64 GHz with high gain and beam-steering capabilities is presented. An inverted T-shaped slotted stub is used with the sectored patch to achieve ultra-wideband properties. In order to resonate the antenna at four different bands, DGS of round bracket slot is etched on the ground. The 1 × 4 phased arrays are used at the top edge and bottom edge of mobile PCB with high gain. The simulation results show that the antenna has four ultra-wide bands: 25.8–29.7, 40.6–44.6, 49.2–53.1, and 62.2–74 GHz with a maximum gain of 16.5 dBi at 51 GHz. The phased array antenna is capable to steer its main beam within ±30° at the 26, 28, and 43 GHz, using appropriate phase shifts of each antenna element. The proposed millimeter wave antenna is particularly suitable for cellular infrastructures and can be a candidate for emerging 5G mobile applications. The availability of an additional 11.8 GHz (62.2–74 GHz) of contiguous unlicensed spectrum will allow the launching of new exciting wireless services.

A scheme has been proposed, modeled and simulated to show an improved system efficiency, battery life and payback period of a 340 kWp peak power grid interactive solar photovoltaic system. In this case, a conventional solar photovoltaic system capable to fulfill 66% energy demands has been modified to meet complete energy demands without an increase in system’s photovoltaic capacity. It has been shown via modelling and simulation on PVSyst that using direct current appliances instead of alternating current appliances, initial power demands are reduced by 58% and conversion losses (DC–AC–DC) of 9.6% are eliminated. These modifications result in an overall increase in the system’s performance ratio from 73.8 to 83.4%, with an increase in energy production from 469.6 to 557.9 MWh. As an outcome, battery life is increased by 1200 duty cycles as the depth of discharge is reduced from 35 to 26%.

This paper presents a novel system design that considerably improves the entrapment of terrestrial ultraviolet (UV) irradiance in a customized honeycomb structure to produce hydrogen at a standard rate of 7.57 slpm for places with a UV index > 11. Thermolysis of high salinity water is done by employing a solid oxide electrolyzer cell (SOEC), which comprises three customized, novel active optical subsystems to filter, track, and concentrate terrestrial UV solar irradiance by Fresnel lenses. The output of systems is fed to a desalinator, a photovoltaic system to produce electrical energy, and a steam generator with modified surface morphology to generate the required superheated steam for the SOEC. A simulation in COMSOL Multiphysics ver. 5.6 has shown that a customized honeycomb structure, when incorporated on the copper–nickel surface of a steam generator, improves its absorptance coefficient up to 93.43% (48.98%—flat case). This results in generating the required superheated steam of 650 °C with a designed active optical system comprising nine Fresnel lenses (7 m2) that offer the concentration of 36 suns on the honeycomb structure of the steam generator as input. The required 1.27 kW of electrical power is obtained by concentrating the photovoltaic system using In0.33Ga0.67N/Si/InN solar cells. This production of hydrogen is sustainable and cost effective, as the estimated cost over 5 years by the proposed system is 0.51 USD/kg, compared to the commercially available system, which costs 3.18 USD/kg.

This paper demonstrated two thulium-doped fiber amplifier (TDFA) configurations, each optimized through a multiparameter optimization algorithm. The two configurations being presented are dual-stage and bidirectional pumped TDFA setups. The selection of thulium-doped fiber lengths and pump powers in both configurations is assisted by the multiparameter optimization algorithm with the goal of maximizing gain. The bidirectional pumping generates a maximum gain of 47.07 dB, while the dual-stage pumping attains an even higher gain of 60.01 dB. Resultantly, the dual-stage pumping configuration appears as the better option. Therefore, an in-depth analysis is performed on a dual-stage TDFA configuration, characterized on system level within the framework of a 12 × 100 Gbps wavelength division multiplexed (WDM) system at channel spacing of 5 nm. The performance is assessed and compared specifically in the S-band in terms of gain, gain ripple, noise figure (NF), Q-factor and bit error rate. By configuring the input power per channel to an optimal value of − 30 dBm, a flat gain exceeding 49.62 dB is obtained with a gain ripple of 6.73 dB across the wavelength range of 1470–1525 nm. The impact of varying input power on gain and gain ripple is also investigated. Furthermore, low average NF of 4.52 dB is obtained. Additionally, a good Q-factor exceeding 10 dB is observed at each wavelength within the specified range. In summary, the research confirms the usefulness of the dual-stage TDFA configuration in improving the efficiency and reliability of optical communication networks.

Presently employed underwater communication systems suffer from issues such as low data rates and short communication ranges. In this paper, a novel hybrid underwater intelligent communication system is proposed and modeled to address both issues. The proposed system provides higher data rate, longer communication range and secure data transmission by employing optical fiber, underwater free space optics (UFSO) and free space optics (FSO). An intelligent routing mechanism governed by Tabu search (TS) algorithm is used for optical path selection based on data traffic, data rate and communication length to maintain a desired quality of service (QoS) while ensuring security of data transmission. For, modeling, optical fiber channel, priority aware (PA) scheduling algorithm for packet-switched optical network (PSON) for data transmission is used whereas for the FSO channel modeling, orthogonal frequency division multiplexing (OFDM) and On–Off Keying (OOK) are used.To simulate underwater turbulent conditions for UFSO channel, scintillation model with gamma-gamma distribution (GGD) is applied. A data rate of 10 Gbps with BER of 10 –9 has been achieved for communication ranges of 140 and 200 m for the cases of turbulent and non-turbulent water conditions. In each of the cases, QoS meeting IEEE standards is ensured.

A scheme has been implemented to improve the system efficiency, battery life and payback period for a hybrid solar photovoltaic system. A standard solar photovoltaic system has been modified to meet the complete energy demands without an increase in system’s photovoltaic capacity and any new investments. A 220 V alternating current system is replaced by a 48 V direct current system. The actual results show that by using direct current appliances instead of alternating current appliances, 50.6% power savings are achieved through reducing load. A 48 V direct current micro grid is implemented and already installed appliances are modified to operate on 48 V direct current from distribution line. Universal and induction motors in rotary appliances are replaced by brushless direct current motors having minimum electro-mechanical and commutation losses. This implemented direct current system reduces the power conversion stages, diminishing the associated power losses and standby losses resulting in the overall increase in the efficiency of system by 9.1%.

Gain characterisation of a laser device is of fundamental importance to assist in the physical understanding of laser materials. Not only does it determine important parameters such as threshold, material loss and transparency current density, but is also a vital source of information regarding the evolution of states as a function of current density and temperature. The differential gain (dg/dn) is of key importance in determining the dynamic performance of a laser. Hence, the important role of gain characterisation has driven researchers to devise improved techniques for spectral gain measurement. This thesis discusses the gain characterisation of 1.3μm quantum dot, commercial Innolume material and bi-layer laser devices. Initially, different gain measurement techniques are reviewed. High resolution spectroscopy and variable stripe length methods are analysed and compared in detail. A technical review is presented for the first time for the commonly used Hakki and Paoli, segmented contact and a new 'integrated mode filter' method for gain measurement. Then the Hakki and Paoli method is used to perform high current density analysis of the gain spectrum of 1.3μm Innolume, quantum dot laser material under continuous wave drive conditions. The device is characterised with and without self-heating effects. The elimination of self-heating effects is achieved by using a longitudinal mode as a junction temperature monitor to keep the junction temperature constant. This allowed an unambiguous study of the continuous wave gain spectrum at average dot occupancy levels up to ~8 e-h pairs per quantum dot. A negative differential gain is observed in both cases. This is shown to be predominantly due to the free carrier effects. As a result, free-carrier related negative differential gain is observed for the first time. A variant to the segmented contact method, which utilises an integrated amplifier and mode filter is demonstrated for the first time. The measurement of the gain/absorption spectrum is critically compared under identical data acquisition conditions as for the integrated mode filter and segmented contact methods. By driving the amplifier section, it is possible to achieve ~3-dB of signal amplification. As a result the measurement of the gain spectrum is achieved over a broader spectral range. Further, it is shown that the integrated amplifier method enables gain measurements at lower current densities as compared to the standard technique. Lastly, the effect of inhomogeneous line width on the lasing line width of ~ 1.3μm quantum dot lasers is studied, as the line width of the transmitter is one of the key factors to determine the dispersion limit for optical communication systems. Two samples, with different inhomogeneous line width are compared under conditions where it is hoped that the effects of homogeneous line width and spectral hole burning are maintained at a constant level. This allows the effects of inhomogeneous line width alone to be studied. A ~30% reduction in inhomogeneous line width is shown to have a significant impact in reducing the lasing line width.

BackgroundEarly detection of patients with clinical deterioration admitted to the hospital is critical. The early warning system (EWS) is developed to identify early clinical deterioration. Using individual patient’s vital sign records, this bedside score can identify early clinical deterioration, triggering a communication algorithm between nurses and physicians, thereby facilitating early patient intervention. Although various models have been developed and implemented in emergency rooms and paediatric units, data remain sparse on the utility of the EWS in patients admitted to general internal medicine wards and the processes and challenges encountered during the implementation.Local problemThere is a lack of standardised tools to recognise early deterioration of patient condition.MethodsThis was a quality improvement project piloted in the clinical teaching unit of a tertiary care hospital. Data were collected 24 weeks pre-EWS and 55 weeks post-EWS implementation. A series of Plan, Do, Study, Act cycles were conducted to identify the root cause, develop a driver diagram to understand the drivers of unexpected deaths, run a sham test trial run of the EWS, educate and obtained feedback of clinical care teams involved, assess adherence to the EWS during the pilot project (6 weeks pre-EWS and 6 weeks post-EWS implementation), evaluate outcomes by extending the duration to 24 weeks pre-EWS and 55 weeks post-EWS implementation, and retrospectively review the uptake of the EWS.InterventionsImplementation of a standardised protocol to detect deterioration in patient condition.ResultsDuring the pre-EWS implementation phase (24 weeks), there were 4.4 events per week (1.2 septic workups, 1.9 observation unit transfers, 0.7 critical care transfers, 0.13 cardiac arrests and 0.46 per week unexpected deaths). In the post-EWS implementation phase (55 weeks), there were 4.2 events per week (1.0 septic workup, 1.9 observation unit transfers, 0.82 critical care transfers, 0.25 cardiac arrests and 0.25 unexpected deaths).ConclusionThe EWS can improve patient care; however, more engagement of stakeholders and electronic vital sign documentation may improve the uptake of the system.