IMPROVING POWER SYSTEM PERFORMANCE USING DEMAND-SIDE MANAGEMENT WITHIN SMART GRIDS ENVIRONMENT

This paper introduces a method to improve the performance of power systems using demand side management to overcome the problems of increasing load demand. Defining suitable demand reduction levels can cause a significant enhancement for the entire network. Therefore, the sensitivity factors related to each load centre are defined to rank the load centres according to their priority. According to these factors, the best required load reduction can be obtained at each load centre. The recommended reduction level has to ensure overcoming the problems associated with the voltage profile and transmission lines overloading due to the increase in load demand. The IEEE 30 bus system is used to highlight the demand-side management strategy under different loading conditions. Some simulation results are introduced to show the importance of considering the sensitivity of load centres when defining the reduction levels at each load centre. The recommended demand side management is compared with the load shedding technique as an emergency action to avoid the problems of line violation and to keep the system stable and secure. According to the obtained results, considerable improvement is achieved in the voltage profile, the network efficiency and power loss without the need for the load shedding. These results encourage the implementation of the introduced technique considering sensitivity of load centres in smart grid environmen

Video Assisted Laryngoscope versus Conventional Macintosh for Pediatric Intubation by Beginner Anesthesiologists

Background: Tracheal intubation is most usually facilitated by the use of a conventional Macintosh laryngoscope. Video and indirect laryngoscopes are becoming more significant tools in the management of the airways in children.Objective: To compare the time of intubation, the number of tries, and the success rate of pediatric intubation by beginner anesthesiologists using a video laryngoscope versus conventional Macintosh laryngoscope.Patients and Methods: This prospective randomized, single-blind clinical was conducted at Zagazig University Hospitals on 52 children aged from 2-6 years who were undergoing elective surgeries. VL Group: (n; 26 patients) intubation using video assisted laryngoscopy (Hugemed type). ML Group: (n; 26 patients) intubation using conventional Macintosh laryngoscope. Duration of intubation, number of trial, hemodynamic response as well as oxygen saturation were recorded at different intervals (base line, after induction, during intubation, after intubation) with assessment of complications.Results: As regard the efficacy and the safety of intubation those patients in ML group had lower intubation time than VL group. There was statistical difference as regard complications of endotracheal intubation as trauma,which was higher in ML group.Conclusion: With the use of a video-aided laryngoscope, it is possible to safely and under supervision to insert an airway into a patient with a difficult airway

Experimental study of sidewall rupture of cylindrical lithium-ion batteries under radial nail penetration

To understand the relationship of the sidewall rupture at different states of charge (SOCs) of cylindrical cells with high specific energy, this work presents the results of radial nail penetration tests of 21700-format cylindrical cells at different SOCs. The thermal runaway and sidewall rupture behaviours were characterised by key performance indicators such as temperature, mass, fire behaviour, and voltage change. In addition, released gases from a subset of tests were measured using the Fourier transform infrared spectroscopy. The change in the internal structure of another subset of cells after the test was observed by X-ray computed tomography. The results show that the sidewall rupture still exists for tests at low SOC (< 30% SOC), but the outcome of thermal runaway and sidewall rupture is milder than those at high SOC (≥ 50% SOC). The average mass loss of cells increases with the increment of SOC. The cell casing thickness is reduced by 12.7% ± 0.3% of the fresh cell, which in combination with the reduction in the strength of the casing material at high temperatures could contribute to sidewall rupture

A simplified mathematical model for heating-induced thermal runaway of lithium-ion batteries

The present study aims to develop a simplified mathematical model for the evolution of heating-induced thermal runaway (TR) of lithium-ion batteries (LIBs). This model only requires a minimum number of input parameters, and some of these unknown parameters can be obtained from accelerating rate calorimeter (ARC) tests and previous studies, removing the need for detailed measurements of heat flow of cell components by differential scanning calorimetry. The model was firstly verified by ARC tests for a commercial cylindrical 21700 cell for the prediction of the cell surface temperature evolution with time. It was further validated by uniform heating tests of 21700 cells conducted with flexible and nichrome-wire heaters, respectively. The validated model was finally used to investigate the critical ambient temperature that triggers battery TR. The predicted critical ambient temperature is between 127 °C and 128 °C. The model has been formulated as lumped 0D, axisymmetric 2D and full 3D to suit different heating and geometric arrangements and can be easily extended to predict the TR evolution of other LIBs with different geometric configurations and cathode materials. It can also be easily implemented into other computational fluid dynamics (CFD) code

Combined numerical and experimental studies of 21700 lithium-ion battery thermal runaway induced by different thermal abuse

Combined numerical and experimental studies have been carried out to investigate thermal runaway (TR) of large format 21700 cylindrical lithium-ion battery (LIB) induced by different thermal abuse. Experiments were firstly conducted with the Extend Volume Accelerating Calorimetry (EV-ARC) using both the heat-wait-seek (HWS) protocol and under isothermal conditions. The kinetic parameters were derived from one of the HWS EV-ARC tests and implemented in the in-house modified computational fluid dynamics (CFD) code OpenFOAM. For the subsequent CFD simulations, the cell was treated as a 3-D block with anisotropic thermal conductivities. The model was verified by the remaining two HWS tests not used in the derivation of the kinetic parameters and validated with newly conducted isothermal EV-ARC tests. Further laboratory tests and model validation were also subsequently conducted using Kanthal wire heaters. The validated model was also used to fill the experimental gaps by predicting the onset temperature for TR in simulated EV-ARC environment, heat generation rate due to different abuse reactions, the influence of heating power and heating arrangement as well as the effect of heat dissipation on TR evolution and the implications for battery thermal management. The present study has identified the TR onset temperature of the considered 21700 LIB to be between 131 and 132 °C. The predicted heat generation rate due to the decompositions of SEI and anode were found to follow similar patterns while that from cathode increase sharply near the maximum cell surface temperature, indicating the possibility of delaying TR onset temperature by optimising the cathode material. The time to maximum cell surface temperature decreases rapidly with the increase of the heating power

Characterizing and predicting 21700 NMC lithium-ion battery thermal runaway induced by nail penetration

Combined numerical and experimental studies are conducted to characterise 21700 cylindrical lithium-ion battery (LIB) thermal runaway (TR) induced by nail penetration. Both radial and axial penetrations are considered for 4.8 Ah 21700 NMC cell under 100% state of charge. Heat generation from the decomposition of the cell component materials are analysed. The maximum cell surface temperature rise and time to reach it in both types of penetration tests are compared. Snapshots from the video footages captured by three high definition and one high speed cameras shade light on the dynamic processes of spark ejection and flame evolution. A generic predictive tool is developed within the frame of the in-house version of open-source computational fluid dynamics code OpenFOAM for nail induced TR. The code treats the cell as a lumped block with anisotropic thermal conductivities and considers heat generation due to nail induced internal short circuit resistance, exothermic decomposition reactions and heat dissipation through convective and radiative heat transfer. Validation with the current measurements shows promising agreement. The predictions also provide insight on the magnitudes of heat generation due to internal short circuit resistance, decompositions of solid electrolyte interphase layer (SEI), anode, cathode and electrolyte. Parametric studies further quantify the effects of cell internal short circuit resistance, contact resistance between the nail and cell, convective heat transfer coefficient and cell surface emissivity on TR evolution

A roadmap toward implementing health technology assessment in Egypt

BackgroundThe Egyptian healthcare system is currently in the early phase of health technology assessment (HTA) implementation. The aim of this study is to propose an implementation roadmap based on the national healthcare system status.MethodsA survey was conducted among Egyptian healthcare sector decision-makers to assess the current and future (preferred) HTA implementation status in Egypt based on a widely used international scorecard methodology. Subsequently, interviews were conducted with experts representing middle- and top-tier management in the Egyptian healthcare system to interpret the survey results and recommend specific actions.ResultsExperts recommended more capacity-building programs for HTA and health economics. Additionally, they proposed establishing HTA units in separate healthcare authorities and merging them into a single central HTA unit in the long term. Regarding the scope of implementation, experts recommended commencing with the assessment of innovative pharmaceuticals, and thereafter, expanding the scope to cover all health technologies in the long term. Additionally, they recommended using innovative tools such as “multi-criteria decision analysis (MCDA)” for tendering, and “managed entry agreements” for reimbursement decisions. Local burden of diseases and costing studies were also recommended to facilitate the implementation of HTA.ConclusionExperts agreed that several actions are required for successful HTA implementation in Egypt, including coordination between HTA bodies, application of an explicit MCDA framework, and strengthening of local evidence generation. To implement these actions, investment in technical capacity-building is indispensable. Most experts favored using multiple and soft cost-effectiveness thresholds. Efforts should be made to publish HTA submission guidelines and timelines of the processes

Feature instructions improve face-matching accuracy

Identity comparisons of photographs of unfamiliar faces are prone to error but important for applied settings, such as person identification at passport control. Finding techniques to improve face-matching accuracy is therefore an important contemporary research topic. This study investigated whether matching accuracy can be improved by instruction to attend to specific facial features. Experiment 1 showed that instruction to attend to the eyebrows enhanced matching accuracy for optimized same-day same-race face pairs but not for other-race faces. By contrast, accuracy was unaffected by instruction to attend to the eyes, and declined with instruction to attend to ears. Experiment 2 replicated the eyebrow-instruc- tion improvement with a different set of same-race faces, comprising both optimized same- day and more challenging different-day face pairs. These findings suggest that instruction to attend to specific features can enhance face-matching accuracy, but feature selection is cru- cial and generalization across face sets may be limited